12

Does anyone know of any bitmap-based 8080/8085 (or, failing that, Z80) computers?

Background: In the late 70s and early 80s, there were a few hobby computers with bitmapped displays. For example, the 1802-based (with the 1864 "Pixie" video chip) COSMAC VIP, ETI-660 and ACE VDU computers, and the 6800-based DREAM. Probably others as well. These computers had a bitmap in VRAM, 64x32 or 64x48 pixels, which was sent to display via DMA. (Usually they also had a hexadecimal keypad, like trainer kits.)

The contemporary 8080 was, as I can gather, mostly used for text, probably because of CP/M. 8080-based arcade cabinets (like Space Invaders) used bitmaps, of course.

But were there any 8080-based hobby microcomputers that used a bitmap display, in the vein of the COSMAC VIP?

tobiasvl
  • 1,489
  • 6
  • 22
  • 3
    Does the ZX Spectrum qualify in 82? Also characters via bitmaps, the ZX80/ZX81 were already doing that earlier on. – Rui F Ribeiro Sep 13 '20 at 18:54
  • 1
    @RuiFRibeiro I'm not intimately familiar with the ZX computers, but for some reason I thought they didn't have bitmapped displays, but used block characters to "build" images. I might be mistaken! If so they certainly qualify, although I'm primarily interested in any 8080-based examples – tobiasvl Sep 13 '20 at 19:04
  • If I recall correctly I played with a Lynx which could do that. – Thorbjørn Ravn Andersen Sep 13 '20 at 19:49
  • 3
    This question reflects a substantial misunderstanding of how things worked: while most systems of that era offered a character mode, any that offered graphics implicitly offered a bitmapped mode as well. – Chris Stratton Sep 14 '20 at 05:23
  • If block characters don't qualify as bitmaps, then what about grid-based character graphics like in the TI-99/4a? – snips-n-snails Sep 14 '20 at 05:56
  • The 1802's bitmap wasn't in VRAM; it was simply ordinary RAM. The "DMA" essentially behaved as though code performed an "LDA R0", except that the result was ignored without being loaded into a register. The 1861 video controller forces eight such cycles on each of 128 14-cycle scan lines, leaving enough time to run three other instructions on each. Typically, code for the VIP would reload R0 on three out of four scan lines, so as to cause groups of eight bytes to get clocked out four times each, so 256 bytes would be clocked out for a 64x32 display, but... – supercat Sep 14 '20 at 16:13
  • 1
    ...one could easily use a higher or lower vertical resolution within the 128-line region by reloading R0 more or less often. The 1861 video chip could have been much more interesting if it had included another 64 shift-register bits, and allowed code to load in either the first or last eight bits via instructions. That would have made it possible for applications to use an eight-character-wide "text mode" using one byte per character, rather than having to use a full bitmap, saving a big portion of the RAM that was typically 1K or less. – supercat Sep 14 '20 at 16:18
  • @supercat Thanks for the details! I was aware that you could have a higher lower resolution; there were a few different CHIP-8 extensions detailed in the VIPER newsletter that took advantage of this, for example. I didn't actually know how the "DMA" worked though. – tobiasvl Sep 14 '20 at 19:27
  • 1
    @tobiasvl: If the 1861 had 64 more bits of shift register, then it would be possible to feed data to the display using instructions, each of which could any register as a memory pointer, rather than DMA. Code on half the scan lines would load the even columns with a 64-pixel delay, while code on the other half would load the odd scan lines without the delay. This would make a wide range of screen formats possible, such as having a 32-pixel wide window with 2-scan-line resolution, surrounded by a border area with 8-scan-line resolution. – supercat Sep 14 '20 at 19:31
  • @ChrisStratton Yeah, I suppose that's probably true. I don't know much about this. But did the VDM-1 offer a bitmapped mode? – tobiasvl Sep 14 '20 at 20:04
  • I still have a set of S100 boards that provided 640x480 bitmap graphics. – Mark Ransom Sep 15 '20 at 18:05
  • @tobiasvl ZX-Spectrum clearly had bitmapped display. "block characters" were only used in basic as a part of custom font, which was drawn by the CPU to the bitmap screen. – lvd Sep 16 '20 at 19:00
  • PMD85 and its clone Didaktik Alfa where 288x256x4color based on i8080 – Spektre Feb 02 '23 at 08:52
  • 1
    I think an S-100 backplane had 8080 CPU boards for it, and I'm pretty sure it had graphics cards that could do bitmapped graphics. I don't have any direct knowledge of them so won't offer this as an answer, but hopefully someone who knows more can. – Wayne Conrad Feb 02 '23 at 16:14

10 Answers10

21

Does anyone know of any bitmap-based 8080/8085 (or, failing that, Z80) computers?

The Kyotronics 85, TRS-80 Model 100, NEC PC8201 and Olivetti M-10 were 8085 based notebook-style computers all based on the KR-85 platform, which had a 640 x 64 pixel graphic LCD screen. It was introduced in 1983.

Here's an example of bitmap graphics on the PC-8201, a 3D maze game that writes graphics data directly to the screen, written in BASIC:-

enter image description here

The PC-8201A also had an optional PC-8241 'CRT adapter', which contained a TMS9918A with bitmap graphics resolution of 256 x 192. This is the same chip that was used in the TI-99/4A, Sega SC3000, MSX etc.

Bruce Abbott
  • 6,673
  • 15
  • 31
16

To start with, there was a whole lot of 8080 based home computers, many of them offering bitmap graphics, but more importantly, the very first general available colour video board, the Dazzler offered bitmap graphics. The Dazzler was most definitely meant for use with an 8080, as it was available at a time before the Z80 could be bought.

For the secondary Z80 question: there were countless Z80-based computers with bitmap. Names like Luxor ABC-800 (1981), Sharp MZ80-B (1981), Colour Genie(1982) and Coleco Adam(1983) spring to mind. And then of course later but even more important systems like Amstrad CPC, or all of MSX. I guess, with some search, less well-known machines made before 1981 could be found.

Toby Speight
  • 1,611
  • 14
  • 31
Raffzahn
  • 222,541
  • 22
  • 631
  • 918
  • 1
    Oh wow, the Dazzler is super interesting. I realize it must have been used in lots of different S100 computers, but were there some specific ones that it was often used in? The Altair for starters, I suppose? – tobiasvl Sep 14 '20 at 19:33
  • 1
    @tobiasvl There is (almost) no special S100. S100 are simple bus boxes exchangeable in all parts. Nothing is fixed. In fact, none of my Altairs still had the original 8080 CPU when I got them (but at least two had them as spare parts:)). The question is like asking if there have been any special PC using a GFORCE 256 graphics card or alike. These are generic add-on for a generic box design. – Raffzahn Sep 14 '20 at 20:26
7

Many of the various Texas Instruments graphing calculators were/are based on the Z80 processor, and those all have bitmap displays. The TI-73 through the TI-86 all had variants of the Z80 processors. Above that, they moved to the Motorola 68k and more recently to ARM9.

Reference

Hannah Schultz
  • 171
  • 1
6

I have started to use computers back in 1986 with a Czechoslovak computer PMD 85 (based on the MHB8080 CPU, a local I8080 clone), which has bitmapped B/W graphics in a 288x256 matrix. A lot of games from the ZX Spectrum has been ported to this computer.

Another Czechoslovak computer, named IQ-151, has a GRAFIK plug-in module, which provides B/W bitmap display 512x256 pixels.

I guess the main reason for bitmap-based graphics in the Czechoslovak computers was simple: there were no advanced ICs like a display controller etc. widely available, so the bitmapped graphics was the easiest way to achieve at least any graphics.

Martin Maly
  • 5,535
  • 18
  • 45
  • heh PMD85 brings up memories ... some ported games where even better than the original for example Saboteur ... – Spektre Sep 30 '20 at 06:58
6

The Belgian DAI computer comes to mind. It had a very sophisticated and flexible graphic system that wasn't a pure bitmap but which memory was shared with the 8080 CPU. The address space was split into CPU-only 8-bit memory and CPU/VDU-shared 16-bit accessed memory (the VDU accessed in 16-bit width, the CPU 8-bit wise). Resolution was up to 528x240 pixels or up to 16 colours per scan line. Each scan line could have its own resolution.

Victor Lambda was also a 8080A computer using a bitmapped display. It was even bitmap-only in the lousy resolution of 112 x 78 in 4 colors. It didn't have a text mode, which made it really a horrible computer to work on, as it could only display 12 lines of 17 characters - yuck! The bad keyboard didn't help. My brother and I almost bought one in 1981.

It was developed in the US but was nearly only commercialized in France. The successor machines Hector were a little bit better with higher resolutions, real keyboard and upgraded to Z80 CPU. There was even a model that was commercialized with Forth instead of Basic.

Toby Speight
  • 1,611
  • 14
  • 31
Patrick Schlüter
  • 4,120
  • 1
  • 15
  • 22
4

Another bunch of 8080-based home computers from USSR with bitmap graphics:

Specialist

Vector-06C (actually had quite advanced bitmap modes!)

Orion-128

PK-01 L'vov (no english wiki page is available)

Irisha (no english page)

Corvette (had both character-based and bitmap-based videomodes)

lvd
  • 10,382
  • 24
  • 62
3

Many UK home computers with Z80s had bitmapped displays. The Sinclair ZX Spectrum (1982) had a 1 bit per pixel bitmap that was transformed into a multi colour display by a separate array of attribute pairs for foreground and background colours. The Amstrad CPC machines (1984) extended this to three different colour bitmap modes, with different tradeoffs between pixel resolution and palette size. Their later PCW machines were also Z80 based and had bitmapped monochrome displays. Japanes MSX machines also had a bitmap graphics mode available.

Mark Williams
  • 4,062
  • 1
  • 23
  • 50
2

The Z80-based Camputers Lynx was notable for only having a bitmapped display, with no character-cell mode.

Because the graphics memory had to be manipulated during the horizontal and vertical sync periods of the video signal (unless you wanted display "snow") graphics were very slow. The lack of any method of scrolling the screen with the software provided in ROM was especially limiting.

John Dallman
  • 13,177
  • 3
  • 46
  • 58
  • 1
    But on the positive side, the regular 6845 cursor signal was wired up as an interrupt source. So you could tie an interrupt to any location on the display, for whatever good that would do you. – Tommy Feb 02 '23 at 02:02
1

The SOL-20 by Processor Technology was based on the 8080A and bitmapped a 1K block of memory to a 64 x 16 line character-only display. There were a few blocky graphic characters, if I recall.

MTA
  • 149
  • 2
1

Not a home computer per se, but the first time I messed with a bitmap display was modifying the rom of the original Space Invaders Arcade. It just used a straight b/w bitmap display with color overlays on the monitor.

Hell the display electronics is so simple you could implement it in a pal or two.

Omar and Lorraine
  • 38,883
  • 14
  • 134
  • 274
Paul Bruner
  • 111
  • 2