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PCMCIA 1.0, SRAM and linear flash cards

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Although mounting remote HDDs over a serial cable to my Olivetti Quaderno was a nice solution, it was not very fast. I wanted to add persistent storage using a PCMCIA card, but Quaderno has just PCMCIA 1.0. I used to work a lot with PCMCIA, but it was always the newer standard (2.0) typical for 386/486 laptops. PCMCIA 1.0 does not support IO devices (so no ethernet cards) or CompactFlash cards (as they are IO cards in the ATA mode). PCMCIA 1.0 can work only with linear memory mapped cards. For linear flash cards, there were two incompatible standards (FTL and MS FFS). SRAM cards had just a single standard. In addition to all of this, simpler devices (industrial, embedded) required attribute memory on the card in order to work at all (fortunately, this laptop supports full Card Services and does not need it).

I took a 4MB PCMCIA SRAM expansion from my Amiga 600 and put it in Quaderno. The ROMDOS drive contains a Microsoft program called MEMCARD.exe (very similar to FDISK.exe, but for early PCMCIA cards), so I used it to format the card, rebooted the machine and got 4MB of persistent storage (the SRAM card has a battery to retain the data even after removing the card from the computer).

These early PCMCIA cards don’t work in Windows out of the box. However, there is already a DOS driver included in Windows 9x. You just need to add two lines in the config.sys and you can use the SRAM card in a “more modern vintage computer” (it still allows you to use the slot with other cards and use hot-plug features). Btw these direct mapped SRAM cards have one big advantage – they are super-fast.

I know it’s almost 30 years late, but I finally understood, how these old PCMCIA devices work…

Olivetti Quaderno PT-XT-20 (1992) – part 2

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You might think that the machine is useless without a working HDD and no floppy drive, but that is not true. Quaderno has a small bootable “ROMDOS” drive with basic system files, COMMAND.COM, a RAMDISK driver (up to 320KB of EMS memory can be used and you still have full 640KB of conventional memory) and Interlink software. This drive is interesting, because it acts like a read-write one. You can edit config.sys and autoexec.bat (the changes are there even after shutdown, if the CMOS battery is ok or AC is connected). You can even copy files there, but if it’s more than a few KB, the system will crash hard (requiring you to
reinitialize the ROMDOS).

With Interlink, you can mount remote HDDs over a serial port. I used it to run VC (Volkov Commander) to edit the config.sys (no EDIT.COM in ROMDOS) and enable the RAMDISK driver. After this, I had my small but fast local storage (non-persistent) and everything bigger was started directly out of the remote HDD from another computer. This is a good way to test the computer before fixing the HDD or installing a flash/SRAM card in PCMCIA 1.0.

Olivetti Quaderno PT-XT-20 (1992) – part 1

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This little machine is an XT-class computer with 16MHz NEC V30HL, 1MB of RAM, double-CGA 640×400 graphics (AT&T6300/Toshiba compatible), MS-DOS in ROM and a 20MB Conner HDD (working in 8-bit mode). Its size and weight are halfway between regular laptops and handhelds (it is ultra-portable even by today’s standards). I got one three years ago and it was dead like almost all of them nowadays. The issue was “easily” fixable by replacing all the SMD capacitors. We replaced the ones on the logic board and the computer booted. However, the screen was not able to retain the contrast value, which made it hardly usable. Also the Conner drive had the head stuck (a common issue, that I want to fix later). We disassembled the lid and replaced a capacitor on the display board. Everything worked flawlessly when disassembled. As soon as we assembled the machine together, it stopped working. We were tired and put the whole thing into storage.

Recently, after three years, we gave the machine another chance. Disassembled it, booted and everything worked ok (except the HDD of course). After assembling it back? No sign of life… The issue was caused by too long legs on the new capacitor in the display board. The legs were sharp and went through the insulation layer on the (metalized) screen cover and shorted the capacitor (I know, shame on us…). Once we fixed this, we were able to put the machine back together and enjoy it. David also replaced cracked internal plastic parts using a 3D printer.

Now we have a trouble-free machine in a perfect shape with just one flaw – a faulty hard drive (and no floppy drive). However, that is not as big issue as one might think…

B&W Macs and Games

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Games on early B&W Macs traded colors for a higher resolution and they often looked very good. However, this was difficult to do in Warlords, a turn-based strategy game with eight nations, where the color was the only way to differentiate between them. The Mac version has unique graphics for buildings and flags (held by warriors) to overcome the lack of colors and the result is surprisingly nice, but the colors on PC are more practical anyway.

Was 8-bit Atari (6502) faster than IBM PC (8088)?

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I was silent for a while as some things required my attention more than old computers. We extended the list of implementations of our Sieve Benchmark and it now supports even 6502. It was developed on Atari 800XL without any modern hardware or software (it’s written in ATMAS II macro-assembler). And it was a pain.

We all remember the lovely days of being young and playing with these simple computers, where programming was often the best way to spend time. These nostalgic memories don’t say the truth how horribly inefficient the development was on these machines in comparison with what came a decade later. David told me that his productivity was about 20 times lower in comparison with developing an assembly program of similar complexity and size on PC. These were one of the biggest reasons for your entertainment:

  • It was easy to fill whole available memory with the source code text. There was a situation when only 100 characters could be added to the text buffer, but about 2000 were needed. That caused that multiple parts were optimized for source code length (except, of course, the sieve routine itself, which was optimized for speed).
  • At the end, it was necessary to split the source code into two parts anyway.
  • Unlike with PCs, the Atari keyboard doesn’t support roll-over on standard keys. It is necessary to release the key before pressing another one (otherwise the
    key-press is not properly recognized).
  • Having a disk drive was a big advantage over tapes. However, the implementation on Atari was very slow and everything took incredible amount of time. Boot into editor? 20 seconds. Loading the first part of the source code? 5 seconds. Loading the second part? 30 seconds. Storing it back? 60 seconds (for just 17 KB). You needed about 160 seconds before trying to run the program after every larger change (including 20 seconds for compiling). Often a minute
    more if the program crashed the whole computer.

Although David never started to use “modern” features like syntax highlighting and code completion and he still programs mostly in the 80×25 text-mode, he said that this was too much for him so I don’t think we will repeat this again soon.

Regarding the results: A 1.77-MHz MOS 6502 in Atari 800XL/XE (PAL) required about 66 CPU cycles to go through a single inner-loop step. If graphics output was disabled during the test, this decreased to just 49 CPU cycles. A 4.77-MHz Intel 8088 needed about 73 CPU cycles to do the same. Thus, 6502 is faster if running on the same clock.

On the other side, the original IBM PC is clocked 2.7x higher than the Atari and 4.7x higher than other important 6502 machines (Apple IIe, Commodore 64). Thus, IBM PC was at least twice as fast in this type of tasks (similar to compiling, XML parsing…). I’m not surprised, but it is nice to see the numbers.

Interestingly, the heavily optimized assembly code running on Atari provides the same performance as compiled BASIC (MS QuickBasic 4.5) running on 20MHz 386DX (interpreted version would be three times slower). This was one of the fastest BASICs out there so it gives you good perspective on how these high-level languages killed the performance back then. David spent a lot of time optimizing the code for both CPUs and used the available tricks for each architecture (like self-modifying code…). If you feel that your favorite CPU should have been faster, you can download the project folder and check the source code. If you create a faster version, please send it to me (but please read the README first, especially the part called “Allowed tricks”).

Also if somebody is able to port the code to Commodore 64, it would be nice to compare the results with Atari (only the disk access, timer and console input/output need to be rewritten). Any expert/volunteer?

Sieve Benchmark download

Transferring old files from Atari floppies

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David asked me if I could help him with transferring all files from the pack of floppy disks he used during the late 80s with an 8-bit Atari (800XE). We are working on the Atari version of our Sieve Benchmark (to compare the performance of old computers) and he told me that, as a kid, he  created many assembly programs that can now speed up the development . The ultimate goal is to compare extremely optimized assembly versions of the benchmark for 6502, Z80 and 8088 to find out, which CPU is faster.

I didn’t have any modern disk emulator for the system so I transferred the files to the PC the old way. I used Atari 800XL and two floppy drives (1050 and XF551). At the beginning, I had just one drive, but then I realized that I was not able to create at least a small RAM disk on a 64k machine with MyDOS – that would allow me to copy files from one disk to another without using multiple drives (this is not straightforward when each of the disks has different density).

Copying files to different disks was necessary. David used the 130KB “ehnanced density” format that is not readable on floppy drives in PC. The Atari XF551 disk drive supports all the Atari formats up to the 360KB double-sided double density that is sort of compatible with PC drives. With the two drives connected to the Atari, I copied the files from the old disks to a few “new” ones and started searching what is necessary to do on the PC side.

At the end, I used two MS-DOS programs – ATUTIL for reading/writing individual files and WRITEATR for creating ATR disk images out of real floppies. All of this took me two evenings, but I’m happy that I didn’t have to use modern hardware to copy files both ways between 8-bit Atari and PC.

(btw David also decided not to use modern hardware so he is programming directly on the Atari 800XL with Atmas II macro assembler from 1985)

Shark demo (1994) running on a SGI O2 workstation

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This is one of the demos that were used by Silicon Graphics and Nintendo to show the graphics features of their upcoming game console (Project Reality / Ultra 64 / Nintendo 64) during CES in 1994.

SGI used an Onyx supercomputer to run the demo. I recorded it in 1024×768 (true-color) on a much less powerful SGI O2 workstation (released in 1996). O2 is based on a graphics architecture similar to what was actually used in Nintendo 64. It was a perfect fit for an inexpensive highly-integrated computer as well as a game console.

I would rather use a different SGI computer (Octane2 was my first choice), but O2 was the only machine that was compatible with my cheap VGA-to-HDMI converter.

Vintage Computers at Work

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We prepared a small room with old computers as a part of a bigger event at work. After careful consideration, we selected Atari 800XL and Commodore Amiga 500 for the contest purposes. Atari was running Space Invaders and each visitor played with the highest difficulty (three lives, level 12). For Amiga, we chose Pinball Dreams and the goal was to get the highest score using just a single ball.

To make the room more appealing, we brought several old computer magazines and 80s props. Curious visitors could also experience ZX Spectrum+ with the Who Dares Wins game. The feedback on our room was very positive and people were talking a lot about their first computers there. However, the biggest surprise for me is that the joystick survived all the players. Some of them gave it a hard time.

Multivision 2000 (Amiga Scan-Doubler)

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Working with old Amiga computers with their original color monitors is always a painful experience. Especially here in Europe where these screens run at 50Hz. Fortunately, my Amiga 2000 is equipped with a Multivision 2000 scan-doubler card that not only doubles H-sync from 15.75kHz to 31.5kHz (to make the output compatible with VGA monitors) but it also allows a user to increase refresh rates up to 100Hz.

I wanted to show this computer on Bytefest (a vintage computer show) and I decided to show it with a CRT (LCDs always ruin the experience). That created an ideal situation to check how this “software controllable refresh rates” feature works. The manufacturer of the card (3-State) bundled a diskette with a simple program that allows you to find the optimum refresh rate using multiple sliders and the way it works is compatible even with old simple VGA screens from the early 1990s.

The picture frequency is increased when a user decreases the number of video lines. Speed of drawing of each line is still the same. The computer just generates fewer lines, which means that a single frame takes less time and the next one can start sooner.

I switched Workbench into the interlaced mode (512 lines instead of 256) and then used the bundled Sync Master tool to decrease the number of lines close to the original non-interlaced resolution. As a result, I got nice and steady 80Hz on a standard VGA screen, which allowed me to work with the computer for hours without eye strain. This is a perfect setup for office/productivity work. However, be prepared that this tool doesn’t work well with applications that open their own screens a display outside Workbench (you need to revert it to default before starting such application).

Nintendo Virtual Boy (1995)

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Virtual Boy was the coolest thing I saw this year during the Bytefest vintage computer show. I knew that this was a commercial failure and expected the worst. However, it was fun to play some of the games and I quite liked the red LED displays. The 3D effect was clearly visible and I didn’t experience headaches from the displays even after nearly an hour of playing.

The only drawback was the mechanical stand that required me to lean forward too much and my (already damaged enough) cervical spine suffered from it. Anyway, I’m happy that I had the opportunity to finally experience this device. I wasn’t expecting to ever see it in our small country.