| Manufacturer | Bally |
|---|---|
| Type | Video game console |
| Generation | Second generation |
| Release date | 1977 |
| Media | ROM cartridge |
| CPU | Zilog Z80 clocked at 1.789 MHz |
| Memory | RAM: 4k-64k (with external modules) RAM, 8k ROM |
| Display | 160x102 (8 colours), 160x88 (2 colours), 320x204 |
The Astrocade is an early video game console and simple computer system designed by a team at Midway, the videogame division of Bally. It was marketed only for a limited time before Bally decided to exit the market. The rights were later picked up by a third-party company, who re-released it and sold it until around 1983. The Astrocade is particularly notable for its very powerful graphics capabilities, and for the difficulty in accessing those capabilities.
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Originally referred to as the Bally Home Library Computer, it was released in 1977 but available only through mail order. Delays in the production meant none of the units actually shipped until 1978, and by this time the machine had been renamed the Bally Professional Arcade. In this form it sold mostly at computer stores and had little retail exposure (unlike the Atari VCS). In 1979 Bally grew less interested in the arcade market and decided to sell off their Consumer Products Division, including development and production of the game console.
At about the same time a 3rd party group had been unsuccessfully attempting to bring their own console design to market as the Astrovision[1]. A corporate buyer from Montgomery Ward who was in charge of the Bally system put the two groups in contact, and a deal was eventually arranged. In 1981 they re-released the unit with the BASIC cartridge included for free, this time known as the Bally Computer System, and then changed the name again in 1982 to Astrocade. It sold under this name until the video game crash of 1983, and then disappeared around 1985.
Midway had long been planning to release an expansion system for the unit, known as the ZGRASS-100. The system was being developed by a group of computer artists at the University of Illinois known as the Circle Graphics Habitat, along with programmers at Nutting. Midway felt that such a system, in an external box, would make the Astrocade more interesting to the market. However it was still not ready for release when Bally sold off the division. A small handful may have been produced as the ZGRASS-32 after the machine was re-released by Astrovision.
The system, combined into a single box, would eventually be released as the Datamax UV-1. Aimed at the home computer market while being designed, the machine was now re-targeted as a system for outputting high-quality graphics to video tape. These were offered for sale some time between 1980 and 1982, but it is unknown how many were built.
In the late 1970s Midway contracted Dave Nutting Associates to design a video display chip that could be used in all of their videogame systems, from standup arcade games, to a home computer system. The system Nutting delivered remains perhaps the most powerful graphics system of the 8-bit generation, and was used in most of Midway's classic arcade games of the era, including Gorf and Wizard of Wor.
The basic systems were powered by a Zilog Z80 driving the display chip with a RAM buffer in between the two. The display chip had two modes, a low-resolution mode at 160 x 102, and a high-resolution mode at 320 x 204, both with 2-bits per pixel for four colors. This sort of color/resolution was normally beyond the capabilities of RAM of the era, which could not read out the data fast enough to keep up with the TV display. The chip used a clever trick to work around this problem, technically "holding the RAS high", allowing them to read one "line" at a time at very high speed into a buffer inside the display chip. The line could then be read out to the screen at a more leisurely rate, while also interfering less with the CPU, which was also trying to use the same memory.
Sadly, on the Astrocade the pins needed to use this "trick" were not connected. Thus the Astrocade system was left with just the lower resolution 160 x 102 mode. In this mode the system used up 160 x 102 x 2bits = 4080 bytes of memory to hold the screen. Since the machine had only 4k of RAM, this left very little room left over for the program's use, which was used for things like holding the score, or game options. The rest of the program would have to be placed in ROM.
The Astrocade used color registers, or color indirection as it was often referred to then, so the four colors could be picked from a palette of 256 colors. Color animation was possible by changing the values of the registers, and using a horizontal blank interrupt you could change them from line to line. An additional set of four color registers could be "swapped in" at any point along the line, allowing you to create two "halves" of the screen, split vertically. Originally intended to allow you to easily create a "score area" on the side of the screen, clever programmers used this feature to emulate 8 color modes.
Unlike the VCS, the Astrocade did not include hardware sprite support. It did, however, include a blitter-like system and software to drive it. Memory above 0x4000 was dedicated to the display, and memory below that to the ROM. If a program wrote to the ROM space (normally impossible, it's "read only" after all) the video chip would take the data, apply a function to it, and then copy the result into the corresponding location in the RAM. Which function to use was stored in a register in the display chip, and included common instructions like XOR and bit-shift. This allowed the Astrocade to support any number of "sprites" independent of hardware, with the downside that it was up to the software to re-draw them when they moved.
The Astrocade was one of the early cartridge-based systems, using cartridges known as Videocades that were designed to be as close in size and shape as possible to a cassette tape. The unit also included two games built into the ROM, Gunfight and Checkmate, along with the simple but useful Calculator and a "doodle" program called Scribbling.
The Astrocade featured a relatively complex input device incorporating several types of control mechanisms: the controller was shaped as a pistol-style grip with trigger switch on the front; a small 4-switch/8-way joystick was placed on top of the grip, and the shaft of the joystick connected to a potentiometer, meaning that the stick could be rotated to double as a paddle controller. By most reports the controllers were excellent, but had the downside of breaking frequently.
On the front of the unit was a 24-key "hex-pad" keyboard used for selecting games and options. Most cartridges included two games, and when they were inserted the machine would reset and display a menu starting with the programs on the cartridge and then listing the four built-in programs. On the back were a number of ports, including connectors for power, the controllers, and an expansion port. One oddity was that the top rear of the unit was empty, and could be opened to store up to 15 cartridges. The system's ability to be upgraded from a Videogame console to Personal computer along with its library of nearly 30 games in 1982 are some reasons that made it more versatile then its main competitors, and was listed by Jeff Rovin as one of the seven major video game suppliers[2].
The Astrocade also included a BASIC programming language cartridge, based on Lee Chen Wang's Palo Alto Tiny BASIC. Supporting BASIC on the system was very difficult, because the display alone used up almost all the available RAM. The solution to this problem was very complex, yet very clever.
BASIC programs were stored in the video RAM by interleaving
every bit of the program along with
the display itself; BASIC used all the even-numbered bits, and the
display got the odd-numbered bits. The interpreter would read out two bytes, drop
all the odd-numbered bits, and assemble the results into a single
byte of code. This was rendered
invisible by setting two of the colors to be the same as the other
two, such that colors 01 and 11 would be
the same (white), so the presence, or lack, of a bit for BASIC had
no effect on the screen. Additional memory was scavenged by using
fewer lines vertically, only 88 instead of the full 102. The end
result of all this was to manage to squeeze out 1760 bytes of RAM
for BASIC programs. The downside was that most of the graphics
system's power was unavailable.
BASIC was programmed, laboriously, through this keyboard by
assigning each of the keys a single command, number and several
alpha characters. These were selected through a set of 4 colored
shift keys. This way you simply typed "WORD"(gold) shift then the
"+" key and got GOTO.
The ZGRASS unit sat under the Astrocade and turned it into a "real" computer, including a full keyboard, a math co-processor (FPU), 32k of RAM, and a new 32k ROM containing the GRASS programming language (sometimes referred to as GRAFIX on this machine). The unit also added I/O ports for a cassette and floppy disk, allowing it to be used with CP/M.
|
|||||
| Bally Astrocade | |
|---|---|
 |
|
| Manufacturer | Bally |
| Active | 1978—1983 |
| Total Games | unknown (4 present) |
| ← Bally Computer System | ZGRASS-100 → |
The Astrocade is an early video game console and simple computer system designed by a team at Midway, the videogame division of Bally. It was marketed only for a limited time before Bally decided to exit the market. The rights were later picked up by a Astrovision, a third-party company, who re-released it and sold it until around 1983. The Astrocade is particularly notable for its very powerful graphics capabilities, and for the difficulty in accessing those capabilities.
Originally referred to as the Bally Home Library Computer, it was released in 1977 but was available only through mail order. Delays in the production meant none of the units actually shipped until 1978, and by this time the machine had been renamed the Bally Professional Arcade. In this form it sold mostly at computer stores and had little retail exposure (unlike the Atari VCS).
In 1981 it was re-released with the BASIC cartridge included for free, this time known as the Bally Computer System, and then the name changed again in 1982 to Astrocade. It sold under this name until the video game crash of 1983, and then disappeared around 1985.
Midway had long been planning to release an expansion system for the unit, known as the ZGRASS-100. The system was being developed by a group of computer artists at the University of Illinois known as the Circle Graphics Habitat, along with programmers at Nutting. Midway felt that such a system, in an external box, would make the Astrocade more interesting to the market. However it was still not ready for release when Bally sold off the division. A small handful may have been produced as the ZGRASS-32 after the machine was re-released by Astrovision.
The system, combined into a single box, would eventually be released as the Datamax UV-1. Aimed at the home computer market while being designed, the machine was now re-targeted as a system for outputting high-quality graphics to video tape. These were offered for sale some time between 1980 and 1982, but it is unknown how many were built.
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The following 4 pages are in this category, out of 4 total.
| Bally Astrocade | |
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| Manufacturer | Midway |
| Type | Console |
| Release Date | 1977 (NA) |
| Media | Cartridge |
| Save Format | None |
| Input Options | 2 Built-In Controllers |
| Special Features | Cartridge Input Power Switch RF Output Power Output |
| Units Sold | |
| Top Selling Game | |
| Variants | None |
| Competitor(s) | None |
| Predecessor | None |
| Successor | None |
The Bally Astrocade (originally known as the Bally Home Library Computer and the Bally Professional Arcade) was a game system released in 1977 by Bally, the original parent company for Midway Games. It was later marketed by an Ohio-based company called Astrovision who changed its name to the Astrocade. The console is particularly notable for its very powerful graphics capabilities, and for the difficulty in accessing those capabilities.
 Bally Astrocade |
 Bally Astrocade Box |
| Second-Generation Consoles |
| Fairchild Channel F | RCA Studio II | Atari 2600 | Bally Astrocade | Magnavox Odyssey 2 | Intellivision | Emerson Arcadia 2001 | ColecoVision | Atari 5200 | Vectrex | Sega SG-1000 |
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This article is a stub. You can help by adding to it.
Stubs are articles that writers have begun work on, but are not yet complete enough to be considered finished articles. |
   | Bally Alley - Bally Alley - The Newsletter for Astrocade Users |
| | Astrocade history at The Dot Eaters - The Dot Eaters - Home Video Game History |
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