On Wed, 4 Mar 1998, Bob Wood wrote: Short form: (more or less) The 8800 was the original machine from MITS. Standard config was a 4 slot backplane, a rather small capacity power supply, front panel, 2mHz 8080 CPU card, and depending on when you bought it either no memory, or with a 256 byte (expandable to 1k) static memory card. No I/O other than the switches and lights on the front panel. ...and painfully small toggles on the front panel switches. And of course the 80 or so individual wires that connected the front panel to the backplane. (let's not get nitpicky... I'm just listing the base configs as I recall them. Pictures, notes, and price list images on my web pages) The 8800a was a slightly uprated version of the 8800. Same front panel and CPU card, a slightly higher capacity power supply, and longer flattened toggles on the front panel switches. (minor cosmetic changes to logo plate) The 8800b was the machine reworked for more serious (read that: business) purposes. A very much higher capacity power supply (which was made available briefly as a retrofit for the 8800/8800a systems), 18 slot backplane, a new CPU card (still a 2mHz 8080) and front panel interface board which now connected to the display (front) panel with a pair of ribbon cables, and additional functions on the front panel allowing the operator to load and display the contents of the CPUs accumulator on the front panel, do direct I/O to/from a port on the front panel, and added the option to make the data lights on the panel operate in one of three modes. 1) standard - unlatched data bus indication 2) port 377 - latched display of output to port 377 (FF if you prefer) 3) I/O - latched display of I/O to/from any port Complete new cosmetic layout of front panel. And... (to round it all out) The 8800b Turnkey. Same as 8800b but without the display (front panel) controls and lights. Front panel interface card replaced by the "turnkey" board which held a boot loader EPROM. Front panel controls reduced to run/stop switch, reset/clear switch, and a keyswitch for power. -jim --- jimw(a)agora.rdrop.com The Computer Garage - http://www.rdrop.com/~jimw Computer Garage Fax - (503) 646-0174