*** M E M O R U M ***

Programming rules 1. Your routine must exit with the new p and q in the same registers as they were on entry. The new PRN is an output only, p and q are both inputs and outputs. (Most people used DE = p, BC = q, HL = PRN in the Basic challenge.) 2. Your routine must not contain self-modifying code ...

Basic challenge Write code for a routine called PRNG16. p, q and the PRN are all 16-bit. Remember a new PRN is obtained just by adding the new p and q. Ignore the carry from the addition as it is very unrandom. p, q and the PRN should be kept in registers. You can use whichever you prefer, however ...

EDIT: The competition has now closed but if you have just found this page and enjoy Z80 programming why not have a go anyway? Memotest 2017 This is a Z80 assembly language challenge, intended to be a fun test of your ability to write the smallest and fastest code possible for a pseudo-random number ...

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I've had another look at the code and the ring timeout period with only two nodes is over half a second at 19200 baud, over a second at 9600 baud, over two seconds at 4800 baud, etc. These are huge times and so I've deleted what I said about patching the ROM to increase the timeout. There could be a...

Bill, if it's a timing problem have you tried selecting a slow baud rate using the NODE BAUD command before initialising the Ring?

Bill, thanks for that info which looks very plausible. "RI10" must stand for "Ring ROM version 1.0" but it certainly wasn't the first version of the software! The Node ROM took months to write and disassembling it with nothing much to go on is not easy. The original source code w...

I don't suppose that anybody involved at the time might have tucked away a notebook giving the variable usage or on the wire protocol? I don't know whether he has any documents squirrelled away, but Tony worked on Node back in the day, so may be able to shed some light on this As Dave says, I worke...

It's the Z80 Family Questions & Answers (http://www.z80.info/zip/ZilogProductSpecsDatabook129-143.pdf) that says /INT, /NMI, /BUSREQ, /WAIT and /RESET should be synchronized to the system clock and /INT and /RESET certainly were in the special reset logic (other signals not needed). It was findi...

Did you know the Z80 has two types of reset, normal and special? No? Well I didn't either until last month. An in-depth study of the Z80 special reset has been completed and please click on the link below for full details. http://www.primrosebank.net/computers/z80/z80_special_reset.htm If you were w...