446 karma · joined November 19, 2014
The programmer chose the filenames: "holes" and "assholes". kudos!
NB: This was MSDOS days when filenames could be a maximum of 8 characters.
I used the "Programming the Z-80" book by Rodney Zaks, which is still on my bookshelf. Some manuals just can't be disposed of!
From memory I recall my favourite instruction - LDIR (Z80 block memory move) is EDB0, and JMP is CA.
Slightly more on topic, I piggybacked a 2716 EPROM onto the back of the TRS-80 ROM so I could get to the previous hard-coded RST locations and interrupt vector of the Z80 processor. In a nutshell, that allowed me to stop/debug/hack running programs without software being able to prevent me.
Fun times.
When armed, the circuit would cause the car to run but stall frequently, blow the horn and lights and misbehave in other ways. Eventually the thief would assume the car was in serious disrepair and abandon it.
Back in the 90s I used the parallel port to interface a PC to a TRS-80 to allow me to store games on the PC. As another commenter has mentioned, the parallel cable isn't fully bidirectional so I used the printer ready, paper out and other signals as imput lines and wrote a nybble (half a byte) based protocol between the two. Fun times.
I've had three in that time due to accidentally leaving it in hotel rooms.
A test of a good mask is if you can see any difference with your eyes open or closed, and if you can feel your eyelashes touch anything if you open and close them. These are excellent and have a satin outer which slides around the pillow rather than coming off or moving.
They include ear pads to block out sound, but I find them a bit uncomfortable and never use them.
Rather than just copy those characters into their ROMs, the clone companies would add "NOT IBM" to get around any copyright claim - with the letters "IBM" in the same memory location as the originals of course. I discovered this when hacking on an Elonex PC - if anyone remembers those.
On inspection we found the rubber had perished, probably as the bottle was around five years old. The replacement cost less than £10, including fluffy cover. We'll be sure to inspect this one more frequently when filling.
Not only does the bottle provide her warmth, to helps ease the pain in her arthritic feet.
I still love coding, learning new stuff and occasionally burning the candle, but I'll never again make it my god.
PADI Advanced, deep, nitrox, 100+ dives mostly in the cold waters of the North Sea.
Edited: added context
They asked me if I wanted to watch, then angled one of the monitors so I could see what they were doing. Laid on side, knees up and relax. Blimely is my bum really that hairy? Don't normally get to see if from that angle.
It feels weird and a little uncomfortable at times, but certainly not painful - even when they found a polyp and removed it with a remote lasso tool of some kind. This later turned out to be harmless.
As is normal for Brits, there was a lot of humour, with the women discussing the latest TV soap opera whilest doing their thing with the "dynorod" tool. As they pump in a gas of some kind to keep the bowl inflated while they work, they tell me it's okay to fart whenever I need. Boy, I think I've got a bad job sometimes. Whatever the nurse with the pointy end gets paid - it's not enough.
It's not exactly pleasant, but necessary and quite interesting to watch inside your own body (not as interesting as watching surgeons put stents into my heart, but that's another story).
Totally agree with Graeme, nothing to fear and massive win if they find things before it's too late. Don't hesitate!
As you might expect from a theoretical physicist, it's based on solid science, with a small amount of poetic licence that he describes in the afterword.
It's been described as "The Day After Tomorrow meets Neuromancer". Not sure I'd quite go that far, but it's a damn good read.
I swear that printer could be heard several streets away!
We had a hard disk cabinet that took "cassette packs" with disk platters in them (maybe 15 inches in diameter). The engineer used to have to come out to it and re-align the heads every couple of weeks as they were not very stable.
I didn't realise there were games for it, dammit. I managed to get hold of a Cobol compiler for it, but with no other technical information about the B80, didn't get very far. No internet in those days kids.
I can't recall if the B80 had it, but there were small satellite workstations that looked similar and had a small silver button under the desk at exactly knee height. On my first day I was introduced to the "shit button". So named because if you accidentally knocked it, it reset the machine and lost all your work. Most people taped a small cover over it.
Fond memories of the B80, and it's big brother the B800 which I used at a different job. Boy was that sophisticated... it needed a paper tape through a "rat trap" to boot it.
I'd forgotten about the cool little LCD display until I looked up your link to it.
At that point the only documentation we had access to was the IBM Technical Reference Manual, which gave the schematics and BIOS listing, but little else.
I was very familiar with GW-BASIC and had written some BASIC code to use the RS232 serial interface from it, so decided to reverse engineer GW-BASIC itself, to work out how it was addressing those chips.
A month or two later, we came across Peter Norton's "Programmers Guide to the IBM PC", which could have saved us weeks.
Exciting times.
ON X GOTO 200,300,400,500 depending if x=1, x=2,x=3...
They'd obviously used the same parser for the standard "If a=1 then goto 200" construct, which allowed an undocumented shortcut of "If a=1, 200" which a few people noticed and started using. However, a later model fixed this, which broke a number of programs.
Level 2 allowed any number of letters in a variable name... but only the first two were recognised as unique. CUSTORDER was seen as the same variable as CUSTLINE.
Still programming, still find Kraftwerk inspiring. Thank you Florien and Rest in Peace. Your music changed my life.
Suppose we have an "age" field, but don't actually know the age of the person, null makes perfect sense.
Otherwise we'd have do do something like using a "magic number" like 0, -1, or a separate field altogether to indicate an unknown value.
Granted, they do need some handling in queries.
Like you, I cut my teeth on the TRS-80 and wrote my first commercial program around 1982, a graphics drawing tool (written in Z80). It sold maybe a dozen copies, but was a start. I've got fond memories of EDTASM and T-BUG, the assembler and debugger.
The TRS80 Technical Reference Manual (1978). This had the full schematics of the computer, explanations, timing diagrams, fault finding tips etc.
Understanding Microprocessors (1979). This taught basic TTL gates, how flip-flops worked, shift-registers, adders and all the other basics.
In my opinion learning this stuff gives you a better understanding of coding, especially with low level languages.
Having no patience to wait for games to load, I linked the two together via the parallel printer interfaces and wrote some Z80 code on either end to allow the TRS80 to store CPC464 programs.
I seem to remember only being able to use 6 of the bits for data, and using a couple of the others to signal as "clear to send" between them. The transfer was very quick, much faster than tape, but wasn't very reliable due to the dodgy connectors on the TRS80.
Using an SD card with the old micros would be miles better.
Using lines which included long REM statements, and various loops, it would play the William Tell Overture.
For background, the Model 1 TRS-80 had virtually no RF shielding and would interfere with many audio devices next to it, so a radio tuned "off station" was ideal.