ICL 1501 Intelligent Terminal
Click big view open
ICL On
The ICL 1501 Intelligent Terminal from Singer Friden.
Tape loader open
Tape loader closed
The tape mechanism detail zoom
signal board of the tape drives
inside viewof the tape drives
The cards cave
The backplane wiring
On this photo you can see two 24-pin ICs
One of the chips is a SN 74198 (8-Bit shiftregister) the other is a SN 74154 (16 Bit Demux.)
I think this is part of the video-generator.
I believe there is no character-generator in the video Controller.
Display consists of 8 * 32 = 256 Characters, with 5 * 7 Dots each.
If every character is stored 5 times in an 8 * 5 byte-array in a
corner of the memory, and there are 32 of those arrays, then there
would be needed 1280 bytes. Programm-code is loaded in the bit-mapped
video area. And I didn't see a chip that I can identify as a
character-generator-ROM!
In this manner, scanning the display also would perform memory-
refresh.
The I/O-board also contains the timing and clock-generator.
I suppose, that refreshing the dyn-RAMs and video-timing is the same. And many of those old computers have complicated multi-
phase clocks. PDP8/E uses a 28-Phase clock!
The 8K Memory board (located on CPU board) half filled with 2K-Bit RAMs, total 8K byte so expandable up to 16 K byte.
The CPU board contains two 24-pin SN 74181 (4-Bit Alus). Registers are made by SN 7475 (4-Bit-Latches)
and SN 7476 (2 J-K-Flipflops) and then there are many many SN 7453
and SN 7450 (AND-OR-INVERT-Gates).
The boards are 8-time multilayer!
The Keyboard
The lit open with reset and load buttons there behind the screen
Here some Sreenshots:
|
computermuseum informatik stuttgart |
