On Thu, Apr 7, 2016 at 9:35 PM, Pontus Pihlgren <pon...@update.uu.se> wrote:
> On Thu, Apr 07, 2016 at 04:08:42PM -0700, Charles Anthony wrote: > > > > I have some code that does an X-11 emulation of the Atari Tempest vector > > graphics display; I'm thinking of wedging it into the simh PDP8 code to > > emulate the 338 and PDP-1 displays. > > > > That woyld be fun :) I could perhaps be used for future PDP-12 > and LINC emulators as well. > > I have read just a little about the 338. I believe it is more or > less a dedicated PDP-8. Can you say how it compares with other > vector displas, such as VC8E? > That is my understanding as well. I haven't actually ever seen any of these beasts; I'm just doing on documentation that I can find, so I am very likely wrong on some points. There is a 338 programming manual at https://archive.org/stream/bitsavers_decpdp8gragmgOct66_2439011/DEC-08-G61B-D_338pgmg_Oct66#page/n0/mode/2up with a the display list opcodes. The VC8E programming is discussed at http://homepage.cs.uiowa.edu/~jones/pdp8/man/vc8e.html. The VC8E has about 8 IO commands, and uses 12 bit coordinates.The commands boil down to set X, set Y and set intensity to 0 or 1. The 338 uses 13bit coordinates; the display has 10 bit resolution. The 338 has scaling, 8 intensity levels, delta move, character ROM, and a 36 page programming manual. There is a description of the VR14/VC8E at http://www.pdp8.net/vr14/vr14info.shtml.; it describes the VC8e as 50K dots per second ont the VR14 monitor, and the 338 as 300K DPS, and mentions that the 338 had a character ROM. http://www.chdickman.com/pdp8/spacewar/ built his own VC8/I for his PDP-8 and runs the PDP-8 version of space war on it. He lists the IOT instructions for the VC8/I; they are similar to the 338. -- Charles
