3 ms·
I did a lot of that on my CPC464 and TRS-80 too. Thanks for rekindling the memory. Relative jumps were the easiest way to make code relocatable, but you were li
by Starwatcher2001 4y ago
I did a lot of that on my CPC464 and TRS-80 too. Thanks for rekindling the memory. Relative jumps were the easiest way to make code relocatable, but you were limited to +/- 128 for an offset.
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.
- jgrahamc 4y agoI used the "Programming the Z-80" book by Rodney Zaks I have that and the 6502 book by Zaks also. I read those books when I was a teenager as if they were tomes filled with wisdom of the ancients. I protected them with plastic book covers and wrote my own notes in the margins in pencil. I worked a Saturday job when I was 16 and spent the money on them. At the time they were so expensive!
- pmontra 4y agoSame plastic cover on Zaks' book (it's still there) and excellent paper quality.
- davidgerard 4y agosame, protective plastic cover and all
- GeorgeTirebiter 4y agoThanks you guys, now the eBay price for those chestnuts has likely doubled! ;-)
- beachy 4y agoDitto, I've been purging my old tech books but I just couldn't let the Zaks book go.