Vectronic's Apple IIgs
Originally Published: May 5, 2004
The IIgs represents a giant leap in the Apple II line. It can still run most earlier Apple II software. The processor is a 16-bit, 2.8 MHz 65SC816. The processor can be slowed to 1 MHz for compatibility with older Apple II programs, especially games that were designed to run slower. My Apple IIgs has 1 MB of onboard RAM with and a 2 MB AE GS-RAM card. Earlier versions of the IIgs (ROM 00 and ROM 01) only had 256K onboard RAM. The IIgs is capable of addressing up to 8 MB of RAM. The user can set up a RAM disk using the GS/OS control panel. My IIgs is currently configured with a 928K RAM disk and 32K RAM cache (see screen shots below).
The IIgs graphics have been significantly enhanced over the IIe. IIgs graphics include a super-hires graphics mode (320 x 200, 16 colors per line colors picked from 4096 colors, or 640 x 200, 16 dithered (4 true) colors per line from 4096 colors). The IIgs has a large set of commonly used routines called the toolbox in ROM similar to the Mac, and an Ensoniq 5503 Digital Oscillator, a music synthesizer chip capable of wavetable synthesis. The IIgs can use an Apple II composite monitor, a television, or an RGB monitor. Apple specially developed the AppleColor RGB 12-inch monitor (model A2M6014) to work with the IIgs' rather unique low horizontal sync rate analog video signal. Third party RGB monitors were also sold.
Despite having 7 free slots like a IIe plus a RAM card slot (similar to the IIe's AUX slot), the IIgs also has one serial printer port, one serial modem port, one disk drive port, one ADB port, one composite video port, one joystick (paddle) port, one RGB monitor port, and a headphone jack. Due to software compatibility reasons, the slots and built in ports are mostly exclusive. Slots 1 and 2 are the modem and printer ports, 3 is the 80-column video, 4 is the ADB mouse, 5 is the 3.5 inch drive support, 6 is the 5.25 inch drive support, and 7 is used for AppleTalk. The control panel (accessible by pressing Control-Open Apple-Escape) lets you make the decisions as to what mode each slot is in: built-in port or whatever is in the physical slot. The Apple IIgs does not have an internal hard drive, but Apple and several third party companies sold high-speed SCSI cards for hard drive connectivity. A few companies like AE sold power supply replacements that contained a hard drive. My IIgs system does not have a hard drive. I am running GS/OS using an 800K floppy disk.
My IIgs system has three disk drives, two 3.5-inch drives and one 5.25-inch drive. The 3.5-inch drives are capable of using 800K 3.5-inch floppy disks. The drives are daisy chained together with the 5.25-inch drive at the end of the chain.
The IIgs uses ProDOS (8-bit or 16-bit) and GS/OS, a sophisticated operating system with the better features from Mac OS. The IIgs has the ability to use DOS 3.3-based applications on 5.25-inch floppies. DOS 3.3 was designed for 5.25-inch disks with a storage capacity of 143K. ProDOS can use either 5.25-inch floppy disks or 3.5-inch disks with a storage capacity of 800K to 1.4 MB. The IIgs does not natively support 1.4 MB floppy disks without the additon of a card. My IIgs is running GS/OS 6.0.1, the final version of GS/OS.
Apple changed the ROM chip three times over the life of the IIgs: ROM 00, ROM 01, and ROM 3. The earliest is ROM 00, released in September 1986. A ROM 00 IIgs would need to have one or two chips (the ROM and possibly also the video graphics controller) upgraded to become a ROM 01 machine. The last revision of the motherboard, known as ROM 3 has a larger ROM (256K versus 128K). The extra ROM allows more parts of the system software to be accessed from there, which allows a ROM 3 to boot and run GS/OS and GS/OS programs slightly faster than a ROM 01. However, the two have identical toolbox functionality from the programmer's standpoint. There is no ROM 2 version of the IIgs. It is simple to determine which ROM your system is running. When you power it up, it should say "Apple IIgs" at the top of the text screen and at the bottom it will say either "ROM Version 01" or "ROM Version 3". If it does not say either, you have a ROM 00. My IIgs is a ROM 3.
A significant feature of a ROM 3 motherboard is the 3.6-volt battery holder. This is the same battery connector used by the Macintosh. It is possible to replace the battery simply by removing the old one and adding a new one. Earlier IIgs boards have a built in battery soldered to the motherboard.