Archive for February, 2013

28
Feb
13

Micro Computer comparison – Part 1

Recently I ran into the rantings of fan boys about the Commodore 64 and the Sinclair ZX Spectrum. I wasn’t very satisfied with the arguments of either side, as they were both filled with bias and ignorance, just like pretty much any flaming on the internet. One C64 fan even claimed the 6502 was faster than the IBM PC (an 8088 @ 4.77Mhz). So I decided to do some reading of data sheets myself to get a more balanced and accurate view of the real potential of the machines. Just to clarify, whilst I own one of each kind of machine, I didn’t have either as a kid and thus don’t have childhood memories to bias my opinion one way of the other.

This is an incredibly long article so read on if you dare!

Continue reading ‘Micro Computer comparison – Part 1’

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25
Feb
13

Corridor 7 for DOS

Title Screen

Title Screen

Corridor 7 was released by Capstone software in 1994 and is a 3d First person perspective shooter which uses a 3d engine based on Wolfenstein 3d. It had the misfortune of coming out after Doom did, which came out the year before blowing away pretty much all the simpler Wolfen-clones with superior everything. At the time we only had our old 386sx (@ 20 Mhz) which couldn’t really play the more advanced games such as Doom, but surprisingly Corridor 7 performed quite ok. We didn’t have Wolfenstein 3d or any of the other shooters around at the time so we thought the demo of Corridor 7 was pretty cool. Unfortunately for me and my brothers, it was basically impossible for us to get registered copies of the shareware games we liked.

In the "Secret" passage

In the “Secret” passage

The graphics support is VGA only as was the case with most games by this time. The graphics are quite dark and atmospheric in stark contrast to games like Wolfenstein and Blake Stone. The graphics engine supports some graphic effects not found in many other games like it, such as walls with transparent elements (such as a windows) and animating textures. Of course Doom has much better graphics and implements these things far better, but for a Wolfenstein engine game the graphics are quite good.

The mini-gun

The mini-gun

Sound support was through the Soundblaster card, which we unfortunately didn’t have on our 386sx, so we played in silence. Playing it more recently on dosbox now reveals that the sound effects are reasonably good, but it’s music and sound effects aren’t as nice as those in Doom. This is probably due to me playing the demo and the developers not having room for higher quality sound in the limited space they had.

Health Regenerator

Health Regenerator

It plays very much like other shooters of the time, but is not as focused on high speed action. Instead of simply finding a level exit, you are tasked with killing all the aliens with in a level. I found the best way to accomplish this is by trying to pick of small number of aliens at a time. If you rush in headlong, you often get swamped by enemies and killed simply because of the number of them. Enemies normally hide around the level until they see you but can also be woken by another one dying or gunshots, so care must be taken to avoid waking too many of them.

The Alien Blaster

The Alien Blaster

The weapons in game are your normal garden variety guns. You start out with a taser that is surprisingly powerful and some kind of automatic weapon. You can find a few other guns in the demo if you know where to look. There is a mini-gun that is by far the most powerful weapon in the demo, it often kills most enemies in one shot, and there is an “alien blaster” that a nastier enemy drops. The blaster is reasonably good, but the mini-gun is significantly better. Near the start of the demo is a box of mines you can use to lay traps for enemies in the case you don’t want to fight them.

Killing floating eyes!

Killing floating eyes!

I had a lot of fun playing Corridor 7 on the old 386sx as a kid, and it still has some merit today. The atmosphere in game is much thicker and spookier than many other games of the time. The game used to scare the pants off me when this weird red face would come flying towards me out of no where, and I would sometimes be caught off guard by some of the enemies. The demo is however a bit short, and levels can be difficult to navigate because of how similar areas can look, but this is a problem that many Wolfen-clones shared and it isn’t as bad as many of the others. I’d imagine that playing through a number of levels could also get a bit repetitive as there is little to vary the game play. However if you’re interested in old school FPS games it’s worth a play as the atmosphere of the game is very good.

19
Feb
13

ZX Spectrum repair

Image clearer - but corrupted

Image clearer – but corrupted

A couple of weeks ago I went to use my spectrum. I modded the circuit to output composite video instead of RF to make connecting it easier, and to clean up the displayed image. The mod was a great success but I discovered bad video ram was causing my machine to not boot up and only display garbage.The garbage had a pattern to it that looked to me like a single bit in the video ram was faulty. Two chips in the video memory were already socketed, probably from a previous repair, and after swapping them I suspected one of them was faulty. The video ram on a spectrum is organised into a bank of 8 4116 memory chips, each one responsible for one bit out of a byte word of video RAM. The original chips are increasingly difficult to find, this makes it difficult to repair them without buying a sacrificial machine to take parts from.

Chips!

Chips!

I searched high and low for some replacement chips and found some AMD equivalent plug-in replacements that I thought would do the job. They are AM9016FPC chips that are 150μs in speed. They are pretty much identical to the original 4116 chips that were originally in the spectrum, so I bought a number of them as spares, in fact enough to replace the entire video memory bank if required.

It's working!

It’s working!

Just this weekend gone the chips arrived and I had time to try them out. So  I dismantled my spectrum, removed one of the Texas Instrument chips in the sockets and replaced it with the new AMD chip. It wasn’t long before I had my spectrum back in working order! The fact that one of the chips had failed concerned me, so I decided to write a simple basic program to test all the memory I could in a simple way, to ensure that no others had died.

So after reading a memory map for the spectrum I banged out a short program to do some simple tests of the ram. Here is some of the code.

Test Program

Test Program

10 LET l=0
20 LET s=25001
30 LET e=65535
40 FOR i=s to e
50 LET c=INT (i/255)
60 IF c=l THEN GO TO 80
65 LET l=c
70 PRINT AT 1,1;"mem addr ";i
80 POKE i,0
90 IF PEEK i=0 THEN GO TO 110
100 PRINT "error ";i;" ";PEEK i
110 POKE i,255
120 IF PEEK i=255 THEN GO TO 140
130 PRINT "error 2 ";i;" ";PEEK i
140 NEXT i

You can adjust this code to test other areas of memory by changing the s and e variables. To run this code you should type CLEAR 25000 first so none of the memory used for basic is overwritten. It tests the upper portion of the contended memory and all of the 32K bank. Progress is printed every 255 bytes. It’s not a very thorough test of the memory as it doesn’t check for cross-links or other memory faults. It could of course be adapted for that, but would take significantly longer to perform the test, unless programmed in assembly.

I ran this on my spectrum and everything appeared fine, I even left the machine on over night and tested again in the morning, so I’m satisfied that the memory is now in good condition.

18
Feb
13

Prospector for DOS

Info Screen

Info Screen

Prospector was written by Lee Chapel back in 1991 as shareware. It is a single screen platform game similar to games like Chuckie Egg that used to run on many old systems in the 1980’s. It is an EGA game that uses the unusual high resolution graphics mode (640x350x16) that very few games used at all back when it was made. It was often supported by tools such as microsoft’s QuickBasic, and Borland Turbo Pascal, which is why that mode is often used most by the more amateur shareware game programmers.

Game Screen

Game Screen

The graphics are clean and take advantage of the higher resolution. They are reasonably attractive and it is pretty easy to tell what the sprites are supposed to be, but the animations for enemies are a bit jerky as there are not that many frames of animation for each of them. The players sprite moves much faster, but so much so that you can’t see the animation unless you are only tapping the keys and moving only slightly.

Sound is very simple and only offers PC speaker support. You basically get a bomb falling sound when you die as you fall towards the bottom of the screen.

Title screen

Title screen

The controls are ok, but take a little bit to adapt to. It is easy to over shoot a ladder or piece of gold because of how fast you move. Jumping feels a bit stiff, and have to move in the direction you want to jump to get momentum before you jump because you can’t change direction in the air. All this makes it harder to move around.

The game play is quite reasonable, but hampered by the controls. There are a number of different enemies that move around a level, some of which are more capable of chasing you than others. The levels start out harder than is necessary, but are a bit easier when you manage to grapple with the controls. Early levels are basic with only ladders and platforms.

The shareware version has only 10 of the 150 levels that the full version of the game has. Getting killed resets your progress through a level, so I didn’t get to see the other features of some of the levels as I was unable to get past the second level. From what we can see on the title screen there appears to be more features and hazards in later levels, with new enemies, elevators and conveyor belts. Prospector was fun for me despite it’s short comings, it requires a bit of patience, and may be difficult to progress very far, but it has some nice ideas and after a bit of practise gets a bit easier to control.

13
Feb
13

Amstrad ALT386 Teardown

Before The teardown

Before The teardown

I have an old Amstrad ALT386 laptop that I got quite some time ago, I use it to do testing of Pascal code for DOS on real hardware as often emulation via Dosbox doesn’t reveal all the bugs. I bought a second machine to use for spare parts as well, so I would hopefully be able to repair faults. It is a 16Mhz 386sx machine with about 4 mega bytes of RAM, it is pretty big for a laptop and was one of the earlier machines designed this way. Unfortunately the machine has stopped working, it powers on but no other signs of life were detectable so I decided to take it apart to see what might be wrong with it.

I had previously had troubles with the video card so I inspected that and tried a few things, but that didn’t work. So I dismantled most of the machine to inspect the main board, riser card and ROM/RAM board. None of these appear to be the problem so I’m still a little bit puzzled as to what might be causing the fault. The machine has a rechargeable Ni-cad for it’s CMOS settings and real time clock, so I suspect that could be an issue. I haven’t had time to test this yet. I may have to remove the battery and fit an alternative cell which shouldn’t be too hard as it is a 3.6V battery pack.

Read more to see some photos of the insides of the machine.

Continue reading ‘Amstrad ALT386 Teardown’

10
Feb
13

Jetpack for DOS

Jetpack Credits

Jetpack Credits

Jetpack was made by Adam Pederson and released by Software Creations back in 1993. The author had created Jetpack and his other DOS games back when he was a teenager. We used to play his puzzle game Squarez extensively back on our 386, and we played this game a bit later after we upgraded  to a 486 some years later.

Main Screen

Main Screen

Jetpack is a single screen puzzle platforming game inspired by games such as Lode Runner. The puzzles revolve around avoiding enemies moving around, and finding all the static gems scattered throughout the level. Unlike Lode Runner there are a number of different baddies with different movement patterns, most of which do not chase you directly. It came with 100 levels, some of which are very hard. You can choose to take on the levels in order, or in random order ensuring you get a very varied game experience. I found there were many levels that were quite difficult later on so I usually play them in order.

Playing a Level

Playing a Level

It has VGA graphics which are quite attractive and well animated. All the sprites move smoothly and collision detection is accurate. The only unfortunate part is there is little variety in the graphics from level to level. There were some graphics packs made for it however, in case you get sick of the original set. The most common set is a christmas graphics pack. The death animations are probably the highlight of the graphics.

The Level Editor

The Level Editor

Sound support comes in the form of PC speaker, Sound Blaster or Ad lib sound card, all of which are quite good. Sound Blaster is obviously the best as it has digitized sound. Not all the sound effects utilise the digitized sound however so you won’t miss out on too much if you only have an Ad Lib card.

The Controls

The Controls

The controls for the game are good and responsive, you do seem to have a little momentum which is unusual for a PC game. I’m guessing this is to accommodate the flight physics for when you are using the jetpack.

Static Items

Static Items

The game has a level editor which was quite easy to use. There was a vibrant community of users who used to share and create levels they had made.At the time I would unfortunately not have been able to take advantage of that as we didn’t have a modem or access to any BBS. As we lived in rural Australia, even if we had a modem our experience would have been terrible as dial-up modems have never worked very well out there.

Enemies!

Enemies!

The original Jetpack for DOS has been available as freeware since 1998, so there is little reason not to give the game a go. The author is working on a sequel/port for modern systems that will make editing and sharing levels easier. So if you like the original, I’d recommend you go to his website and have a look at the new version and support him. You’ll find his site here.

04
Feb
13

WindowMaker on FreeBSD

The basic WindowMaker interface plus a few applications.

WindowMaker on FreeBSD

This weekend I decided it was time to upgrade the software on the two functional Sun Sparc systems I have. I have FreeBSD on the newer of the two machines, and had been trying various window managers to use. The older Sparc has FVWM (recently upgraded to the latest version) on it so whilst it is really my favourite for reasons of nostalgia, I felt I’d like something different. I had tried XFce, but many features of it were broken on the FreeBSD/Sparc64 platform. So I installed a few other window managers to see what they were like.

I had never installed WindowMaker before but had certainly heard of it. I remember looking through many package lists to see many of the dock apps, and wondering about the window manager itself. WindowMaker has a similar style to the old NeXT workstations operating system called NeXTStep the system that would eventually become mac OSX.

The first thing I noticed when I fired it up was how minimalist it appeared to be. I found the root menu relatively quickly and managed to work out most of how it works within a few hours. I was quite impressed with how fast the interface responded when I clicked on items, although FVWM is a slight bit faster but not by much. There is a very nifty configuration program built-in that controls pretty much everything you could want to change. This makes it very newb friendly, I was able to set up my desktop the way I wanted it very quickly.

It isn’t the most pretty of window managers however, and there is no pager built-in. Workspaces are managed by the clip icon, usually at the top left of the screen. When using it via X on the local network it was quite fast, but over a VPN or SSH connection it became quite sluggish when FVWM maintains reasonable speed. I’ve heard that it can get slow if you have a large number of dock apps running.

Overall I quite like WindowMaker, whilst it isn’t a replacement for FVWM for me, it will be a nifty interface for my newer sparc machine. I like that I can configure most things with the user interface, and the large number of dock apps available for it. It isn’t so useful when I’m connecting into my machine externally however as the speed drops of significantly. It’s available on all the different distributions and the various BSD systems.




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