UDG - Just UDG...
- 1024MAK
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- Location: Looking forward to summer in Somerset, UK...
Re: UDG - Just UDG...
On a real ZX81/TS1000, to get UDG, you need a memory chip to supply different data compared with the data in the BASIC ROM chip. Until the ZXpand and Andy’s UDG board, the only way (*) was to buy/make an internal ROM/RAM board and fit it in place of the BASIC ROM. They could have the BASIC ROM, a custom ROM, and a SRAM chip.
You could fill the SRAM chip with whatever character set you liked. But while this set is in use, the character set in ROM is not available, that is, you can’t mix and match. But you can copy the character data from the BASIC ROM.
(*) not including high resolution graphics systems and techniques.
Mark
You could fill the SRAM chip with whatever character set you liked. But while this set is in use, the character set in ROM is not available, that is, you can’t mix and match. But you can copy the character data from the BASIC ROM.
(*) not including high resolution graphics systems and techniques.
Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
Re: UDG - Just UDG...
My ideal would be a software only solution. Looks like WRX maybe the closest path there (?)....
Zeddy: ZX80, ZX81/ZXpand, TS1000/ZXpand, TS1500/Zxpand+,Printer
Speccy: 48k, +, +2, +3, TS2068, "Bare Metal" Pi, Next KS2, IF1/Microdrives/Vdrive/Light Gun/VGA-Joy
QL: Minerva/QL-VGA/Custom PSU
C5: 24v, LiFE battery, Disc brakes
Speccy: 48k, +, +2, +3, TS2068, "Bare Metal" Pi, Next KS2, IF1/Microdrives/Vdrive/Light Gun/VGA-Joy
QL: Minerva/QL-VGA/Custom PSU
C5: 24v, LiFE battery, Disc brakes
Re: UDG - Just UDG...
If you look at Nuclear Invaders by Kelly Murta, he has made a game in Forth with UDG. After that he has made a WRX version with a few extra routines, that simulate UDG in WRX mode. The Forth source is included with the program, however the UDG-to-WRX routines you have to decompile yourself.
Re: UDG - Just UDG...
I made an UDG-routine for my SHOGUN game and that routine was converted to the USCII-routine so it was possible to use UDG in BASIC.mrtinb wrote: ↑Mon May 03, 2021 9:00 pm If you look at Nuclear Invaders by Kelly Murta, he has made a game in Forth with UDG. After that he has made a WRX version with a few extra routines, that simulate UDG in WRX mode. The Forth source is included with the program, however the UDG-to-WRX routines you have to decompile yourself.
Re: UDG - Just UDG...
You always have the Pseudo High Res Graphics alternative which doesn't require hardware mods, it's a software only solution.
Camilo Eid - ZX81
Re: UDG - Just UDG...
Thanks.
Zeddy: ZX80, ZX81/ZXpand, TS1000/ZXpand, TS1500/Zxpand+,Printer
Speccy: 48k, +, +2, +3, TS2068, "Bare Metal" Pi, Next KS2, IF1/Microdrives/Vdrive/Light Gun/VGA-Joy
QL: Minerva/QL-VGA/Custom PSU
C5: 24v, LiFE battery, Disc brakes
Speccy: 48k, +, +2, +3, TS2068, "Bare Metal" Pi, Next KS2, IF1/Microdrives/Vdrive/Light Gun/VGA-Joy
QL: Minerva/QL-VGA/Custom PSU
C5: 24v, LiFE battery, Disc brakes
Re: UDG - Just UDG...
But there is no easy way to use it from Basic, like the great USCII-routine. And you can’t use the ZX81 charset, unless you use the same “I”-value as the ROM does.
However it would be possible to make a routine, like USCII, where you can display the normal characters, and custom characters where the 8 patterns for the char is taken from 8 different characters. Then some funny characters can be made, but they will be somewhat limited.
To make it even more flexible you can use the source from Paul Farrow’s Celebration Demo. With that routine you can change the “I”-value for each scan line on the screen.
Re: UDG - Just UDG...
I have no interest doing anything in basic. I'll check out Pauls stuff. I'm really looking to just remap a couple characters for use from assembly replacing a few of the stock characters - or replacing all of them if that's easier.
Zeddy: ZX80, ZX81/ZXpand, TS1000/ZXpand, TS1500/Zxpand+,Printer
Speccy: 48k, +, +2, +3, TS2068, "Bare Metal" Pi, Next KS2, IF1/Microdrives/Vdrive/Light Gun/VGA-Joy
QL: Minerva/QL-VGA/Custom PSU
C5: 24v, LiFE battery, Disc brakes
Speccy: 48k, +, +2, +3, TS2068, "Bare Metal" Pi, Next KS2, IF1/Microdrives/Vdrive/Light Gun/VGA-Joy
QL: Minerva/QL-VGA/Custom PSU
C5: 24v, LiFE battery, Disc brakes
Re: UDG - Just UDG...
- Use dr. Beep's USCII if you want to code for WRX (needs WRX enabled RAM), or
- Use Paul's code if you need to run with PSG (Pseudo Hires Graphics) on unmodified hardware.
Re: UDG - Just UDG...
See my SHOGUN in hires. It uses WRX-graphics and text all addressed with a chr.
CHR up to 191 are printed as normal or inverted, above 191 are user graphics. The same routine is used in USCII.