Basic/Four Corporation Model 7250 terminal

Back on the subject of the terminal :-). I opened up the case and had a look inside. The case is similar to the ADM terminal in design: you unscrew two screws underneath the front and then fold open the lid. The CRT and the high voltage drive circuitry is attached to the lid. The power supply and logic board are mounted to the underside portion of the case. The oldest date code I could find on the chips was 77 31 and the youngest date code I could find was 79 02. The logic board circuit card is labelled in the circuit traces as VDT LOGIC & CONTROL ASSY 901990- REV S/N BD DETAIL 904058 REV A with a serial number label affixed to the board and "basic/four" with a logo in the center front of the board between the components. The keyboard is made by keytronic and is the one circuit card that has date codes from 1979. The logic and control board has the earlier date codes, with most of them being from 1978 but the 7474s are all 1977. Its always good to discover a new TTL based terminal with an original design (i.e. not OEMed from someone else). CRT terminals are still around, but certainly by the 1990s they were all starting to look alike. Finding a new terminal from the 1970s is always fun! Its also got that character of a "terminal designed exlcusively for XYZ application". The keyboard is made by keytronic and has a layout like this: 1,! 2," 3,# 4,$ 5,% 6, 7,' 8,( 9,) 0,+ :,* -,= @,; ctrl Q W E R T Y U I O P & <- mode A S D F G H J K,[ L _,\ car/enter shift Z X C V B N,^ M,] ,,< .,> ? shift Based on the symbols on the shifted letter keys, I'm not even sure it will do lower case. The keypad on the right side of the keyboard has this layout /------\/--\/-------\/-----\ | - | , | escape | clr | \______/\__/\_______/\_____/ / \/ \/ \/ \/ \ | 7 | 8 | 9 | || IV | \__/\__/\__/| |\_____/ / \/ \/ \| |/ \ | 4 | 5 | 6 | I || III | \__/\__/\__/| |\_____/ / \/ \/ \| |/ \ | 1 | 2 | 3 | || II | \__/\__/\__/| |\_____/ / \/ \| |/ \ | 0 | . | || print| \______/\__/\_______/\_____/ At this point its not at all clear to me what the communications dialog looks like when you use the mode key, the print key or the clr key. I notice this thing has no "local/line" switch on it, so perhaps that is controlled by mode. Clr might just be hardwired to send a certain sequence to the host and expect the host to send the clear screen command, who knows. The I, II, III, and IV keys are interesting in that it looks like these might be mapped to the four basic arithmetic operators add, subtract, multiply and divide. I believe that is where the "basic four" comes from in the company's literature. This guy will need a careful inspection of all his circuitry and a little bit of a cleanup before I'm willing to apply power. -- "The Direct3D Graphics Pipeline" -- DirectX 9 draft available for download <http://www.xmission.com/~legalize/book/download/index.html> Legalize Adulthood! <http://blogs.xmission.com/legalize/>