Bally Astrocade

Lore & Background

In the late 1970s, Midway contracted Dave Nutting Associates to design a video display chip for use in both arcade games and a home computer system. The chipset supported a relatively high resolution of 320×204 in four colors per line, but accessing this mode required memory faster than the common 2 MHz dynamic RAM of the era. The system was originally announced as the Bally Home Library Computer in October 1977 and made available for mail order in December 1977. Due to production delays, units first reached stores in April 1978, rebranded as the Bally Professional Arcade. 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 1984. It sold under this name until the video game crash of 1983, and then disappeared around 1985. The Astrocade used a Zilog Z80 driving the display chip with a RAM buffer in between. The display chip had two modes: low-resolution at 160 × 102 and high-resolution at 320 × 204, both with 2 bits per pixel for four colors. The higher resolution mode required page mode addressing to read one line at a time into a buffer inside the display chip, but on the Astrocade the pins needed for this trick were not connected, leaving only the lower resolution mode. This mode used 4080 bytes of memory for the screen, leaving very little room for program functions. The system used color registers (color indirection) so the four colors could be picked from a palette of 256 colors, and color animation was possible by changing register values. An additional set of four color registers could be swapped in along a line, allowing two screen halves split vertically. The Astrocade did not include hardware sprite support but did include a blitter-like system; writing to ROM space would cause the video chip to apply a function and copy the result to RAM. The Astrocade was one of the early cartridge-based systems, using cartridges called Videocades designed to resemble cassette tapes. The unit included two built-in games (Gunfight and Checkmate), a Calculator, and a doodle program called Scribbling. The controller featured a pistol-style grip with a trigger switch, a small 4-switch/8-way joystick on top, and a potentiometer allowing the stick to rotate as a paddle controller.

Reader's Guide

The Bally Astrocade's significance lies in its advanced graphics hardware that was largely inaccessible due to design choices and memory limitations. The system's high-resolution mode (320×204) was beyond the capabilities of common RAM, and the necessary pins to enable the workaround were not connected, leaving only the lower 160×102 mode. This severely limited the available RAM for programs, as the display alone consumed almost all of the 4 KiB. The system's blitter-like system allowed software-driven sprites, but placed the burden of redrawing on the programmer. The Astrocade's BASIC cartridge, Bally BASIC, stored program code in video RAM by interleaving bits with the display, sacrificing graphics power for program space. The system's ability to be upgraded from a video game console to a personal computer, along with its library of nearly 30 games in 1982, made it more versatile than its main competitors. However, limited retail exposure and Bally's exit from the market prevented widespread adoption. The system was re-released by a third party and sold until around 1984, eventually disappearing after the video game crash of 1983. The planned ZGRASS-100 expansion system was not ready before Bally sold the division; a small number may have been produced as the ZGRASS-32. The ZGRASS system combined into a single box was eventually released as the Datamax UV-1, targeted at outputting high-quality graphics to videotape.

Did You Know?

• The Astrocade's high-resolution mode (320×204) was not accessible on the released console because the necessary pins were not connected.
• The controller combined a pistol grip, joystick, and paddle control in a single unit.
• The top rear of the console could be opened to store up to 15 cartridges.

From Midway's Drawing Board to Bally's Showroom

In the late 1970s, Midway—then operating as the video game arm of the Bally corporation—sought a unified display solution that could serve everything from floor-standing arcade cabinets to a consumer home machine. They turned to Dave Nutting Associates, who delivered a video display chip capable of rendering 320×204 pixels with four colors per scan line. That same chipset went on to power beloved arcade titles like Gorf and Wizard of Wor, cementing its reputation within the industry. The home-facing product built around this hardware was first unveiled in October 1977 under the name Bally Home Library Computer and became available through mail order by December of that year. However, manufacturing setbacks meant no physical units actually reached retail shelves until April 1978, at which point the branding had shifted to Bally Professional Arcade. The machine was marketed only briefly before Bally chose to withdraw from the consumer space entirely, leaving a technically impressive but commercially underexposed console to find its way through a series of ownership changes over the following years.

The Resolution That Never Was

The Astrocade's display chip was designed with two operating modes: a modest 160×102 resolution and a far more ambitious 320×204, both using two bits per pixel to produce four colors. The higher mode demanded memory bandwidth that the standard 2 MHz dynamic RAM of the late 1970s simply could not sustain. The intended workaround was a page-mode addressing scheme that let the chip grab one scan line at a time into an internal buffer, then trickle that line out to the television at a gentler pace while minimizing contention with the Z80 CPU sharing the same memory bus. Yet on the actual Astrocade hardware, the specific pins required to enable that high-speed line transfer were left unconnected. The result was a console permanently locked into the lower 160×102 mode, where the framebuffer alone consumed 4,080 bytes of the machine's meager 4,096-byte RAM pool. That left a mere sixteen bytes for runtime data such as scorekeeping or option tracking, pushing virtually all game logic into read-only memory. A powerful chip, stranded by a wiring decision.

A Console Without a Home

The Astrocade's commercial journey was marked by constant reinvention and displacement. After its 1977 mail-order debut as the Bally Home Library Computer, production slippage pushed store availability into 1978 under the Bally Professional Arcade name, and the unit found a narrow audience primarily in computer shops rather than the broad retail aisles where the Atari VCS dominated. By 1979, Bally's interest in the consumer segment had waned, and the company divested its entire Consumer Products Division. Around that same period, a separate group had been struggling to bring their own console, the Astrovision, to market. A Montgomery Ward executive overseeing the Bally hardware happened to connect the two parties, and a licensing deal followed. In 1981 the machine returned to shelves bundled with a free BASIC cartridge and rebranded as the Bally Computer System; a year later it settled on the name Astrocade. It lingered on the market until the 1983 video game crash and faded from view by roughly 1985.

Drawing Without Sprites

Unlike its contemporary the Atari VCS, the Astrocade offered no dedicated hardware sprites. Instead, its designers provided a software-driven blitter mechanism: memory addresses above 0x4000 were reserved for the display, while addresses below held ROM code. When a program wrote into the normally read-only ROM region, the video chip intercepted the data, applied a selectable function—XOR, bit-shift, or similar—stored in a dedicated register, and wrote the transformed result into the corresponding RAM location. This allowed developers to render any number of movable objects on screen, at the cost of manually redrawing each one whenever it changed position. Color handling was equally flexible: four on-screen colors were drawn from a 256-entry palette via indirection registers, and a horizontal blank interrupt permitted line-by-line palette swaps. A second quartet of registers could be injected mid-scanline, effectively splitting the screen into two vertical halves. Originally conceived for a side-mounted score panel, programmers quickly repurposed the trick to fake an eight-color display. Cartridges, dubbed Videocades, were sized to mimic a cassette tape, and the base ROM shipped with Gunfight, Checkmate, a Calculator, and a drawing toy called Scribbling.