I started playing around with the mainframe at the college where my dad was a security guard. I was the only nine-year-old with a user account. Heh heh. From there I went on to hanging out in Radio Shaft and playing around with the TRS-80 Level I (before they called it the Model I.)
The first computer of my own was the Atari 800. Apple was nice, but I avoided it because Atari had the best graphics and sound hardware in its day. Besides, Star Raiders was the killer app, and I still play it with the free Atari800Win Plus emu every now and then.
I did a little hacking too, thanks to Omnimon. It was a circuit board that plugged into one of the ROM chip sockets, and it filled the unused $C000-$CFFF block of memory with a program that allowed one to interrupt anything with a press of Select and System Reset. It was now possible to take the machine code of a program that's running (even game carts) and do some simple disassembly. It also had a mini assembler that worked one instruction at a time. The Omnimon board also had one wire patched into the ROM that held the top of memory (to $FFFF) which is how it interrupts the boot process. (The last few bytes were pointers used by warm and cold starts.) There was also a three-position toggle switch that I added to the case. If I remember right, one setting allowed interruption, one restored the original ROM pointers, and the last position made the $C000 block disappear so the machine looked unaltered. Unfortunately, the later models used that memory area (probably for the rainbow logo and that sophisticated "self-test.") I think I saw a mention of a version of Omnimon designed for the newer machines, but I had the original.
Oh yeah, I also added a little switch in the bottom to silence the internal speaker since I would be writing programs through the night. At one point I upgraded the beast from a CTIA to GTIA chip and enjoyed the extra graphics modes that were in the later models, and I took out the power LEDs and replaced them with green ones. Ahh, the memories!
I remember being in awe of the bank switching technique used in the macro assembler cartridge I owned. I wasn't to shabby at speaking 6502 and Antic display list instructions. Heh heh.
That old computer died eventually. The keyboard needed to be replaced, and by that time they were impossible to find and cost over $100. After using a driver I wrote that made the escape key a space bar substitute (unless shift was pressed,) the computer was fried by a power surge. It died slowly over the course of a month, and towards the end started rebooting spontaneously. I laid it to rest and got myself a 65XE. A few years down the road that computer was stolen from storage, but they didn't get my carts and disks. I hope they had fun with it, and the high-pitched whine my poor old 13" TV had. Heh heh heh.
Re:So did Sinclair ZX80
on
Scanjet Music
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· Score: 1
I just hung out at the local Radio Shaft when I was a kid and played with their "Level I." Before that, I played with the mainframe at the college.
I discovered that flicking the power switch off and on quickly sometimes produced double-sized text on the screen, but only odd-numbered keystrokes were displayed. I found it funny that when I went to the next town's RS that had the Level II, the large text was an option that could be selected. The hardware was there, but the support wasn't unless you spent a few more bucks.
Ooooh, just noticed this on the TRS-80 site: The Model 3 was Tandy's second personal computer. One of the reasons it was developed was because the FCC instituted regulations about the RF emissions generated by computers (and other electronic devices). The Model 1 was completely unshielded (a fact many owners who also like TV and/or radio discovered the hard way), and was unable to pass the emission restrictions.
Interesting. I remember seeing the Model III but never a "Model II." I thought it was to avoid confusion with "Level II," but that site just educated me. Heh heh.
Anyway, when I was older and able to get a machine, I got the Atari 800. That computer could also produce tones on an AM radio, but by the time I learned 6502 Assembler, I was more concerned with the undocumented POKEY chip features like combining two channels for 16-bit sound, having direct control over the speaker voltage level (such as the "ET phone home" spoken on the game cartridge,) and my personal favorite: the bit that lowers all output by one octave. (This may have contributed to what became my favorite instrument to play!)
Re:So did Sinclair ZX80
on
Scanjet Music
·
· Score: 1
Heh, I remember that sort of thing done on a TRS-80 (before they called it the "Model 1" to give my age away.) One would put a radio tuned to a dead spot on the AM band next to the machine. You can still do that to hear the machine cycles happening, but turning them into music was an artform.
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I started playing around with the mainframe at the college where my dad was a security guard. I was the only nine-year-old with a user account. Heh heh. From there I went on to hanging out in Radio Shaft and playing around with the TRS-80 Level I (before they called it the Model I.)
The first computer of my own was the Atari 800. Apple was nice, but I avoided it because Atari had the best graphics and sound hardware in its day. Besides, Star Raiders was the killer app, and I still play it with the free Atari800Win Plus emu every now and then.
I did a little hacking too, thanks to Omnimon. It was a circuit board that plugged into one of the ROM chip sockets, and it filled the unused $C000-$CFFF block of memory with a program that allowed one to interrupt anything with a press of Select and System Reset. It was now possible to take the machine code of a program that's running (even game carts) and do some simple disassembly. It also had a mini assembler that worked one instruction at a time. The Omnimon board also had one wire patched into the ROM that held the top of memory (to $FFFF) which is how it interrupts the boot process. (The last few bytes were pointers used by warm and cold starts.) There was also a three-position toggle switch that I added to the case. If I remember right, one setting allowed interruption, one restored the original ROM pointers, and the last position made the $C000 block disappear so the machine looked unaltered. Unfortunately, the later models used that memory area (probably for the rainbow logo and that sophisticated "self-test.") I think I saw a mention of a version of Omnimon designed for the newer machines, but I had the original.
Oh yeah, I also added a little switch in the bottom to silence the internal speaker since I would be writing programs through the night. At one point I upgraded the beast from a CTIA to GTIA chip and enjoyed the extra graphics modes that were in the later models, and I took out the power LEDs and replaced them with green ones. Ahh, the memories!
I remember being in awe of the bank switching technique used in the macro assembler cartridge I owned. I wasn't to shabby at speaking 6502 and Antic display list instructions. Heh heh.
That old computer died eventually. The keyboard needed to be replaced, and by that time they were impossible to find and cost over $100. After using a driver I wrote that made the escape key a space bar substitute (unless shift was pressed,) the computer was fried by a power surge. It died slowly over the course of a month, and towards the end started rebooting spontaneously. I laid it to rest and got myself a 65XE. A few years down the road that computer was stolen from storage, but they didn't get my carts and disks. I hope they had fun with it, and the high-pitched whine my poor old 13" TV had. Heh heh heh.
I discovered that flicking the power switch off and on quickly sometimes produced double-sized text on the screen, but only odd-numbered keystrokes were displayed. I found it funny that when I went to the next town's RS that had the Level II, the large text was an option that could be selected. The hardware was there, but the support wasn't unless you spent a few more bucks.
Ooooh, just noticed this on the TRS-80 site: The Model 3 was Tandy's second personal computer. One of the reasons it was developed was because the FCC instituted regulations about the RF emissions generated by computers (and other electronic devices). The Model 1 was completely unshielded (a fact many owners who also like TV and/or radio discovered the hard way), and was unable to pass the emission restrictions.
Interesting. I remember seeing the Model III but never a "Model II." I thought it was to avoid confusion with "Level II," but that site just educated me. Heh heh.
Anyway, when I was older and able to get a machine, I got the Atari 800. That computer could also produce tones on an AM radio, but by the time I learned 6502 Assembler, I was more concerned with the undocumented POKEY chip features like combining two channels for 16-bit sound, having direct control over the speaker voltage level (such as the "ET phone home" spoken on the game cartridge,) and my personal favorite: the bit that lowers all output by one octave. (This may have contributed to what became my favorite instrument to play!)
Heh, I remember that sort of thing done on a TRS-80 (before they called it the "Model 1" to give my age away.) One would put a radio tuned to a dead spot on the AM band next to the machine. You can still do that to hear the machine cycles happening, but turning them into music was an artform.