The HP 1350A has two 10-bit digital to analog converters that appear to drive an analog vector generator that is very similar to those used in some of the older vector arcade games. The memory capacity is 2048 instructions, and each instruction can be a (light or dark) vector, or a letter or symbol. All addressing is absolute, and there is no short-vector relative addressing like an Imlac PDS-1 or VT-11 vector generator. The 2048 word memory can be divided up into 'files' that can be selectivly blanked, cleared or overwritten. A simple TTL state-machine drives X and Y axis ALU/Accumulators that feed the discrete transistor-ladder DAC's for each axis. Some logic looks at the vector lenght and optimises the writing speed and Z axis intensity, but this is by far the weakest feature of the device. Some shorter to intermediate lenght vectors are drawn too brightly, enough to be noticable. There are some ROM subroutines that generate letters and symbols, and an additional socket allows custom symbols to be displayed with a single-word instuction. There does not appear to be any form of light-pen input as on the VT-11 and some (optional) Imlac's. To get a HP 1350 working, you need some coaxial cables and an X/Y monitor. I've used a HP 1335, as well as some Tektronic's X/Y monitors (420 and 611). I've found that with the Tek monitors I can get a perfect X/Y aspect ration by using a 75 ohm and 50 ohm coaxial terminator for the X and Y axis (using BNC T fittings). You also need some sort of HPIB host to drive the thing, although a PIC-based RS-232 adaptor should be quite easy to design. The basic 'GTML' language is ASCII-based. You address the device (like any HPIB listener) and send it strings of commands and data. A set of LED's on the front pannel will show what context the data is being read in (commands versus data). As the commands are read, the HP 1350 will alter its internal memory and start to draw vectors and symbols. Lines are drawn with the PA (plot absolute) instruction: PA(X coordinate),(Y coordinate);(X coordinate),(Y coordinate) These can be strung together for form complex lines like: PA0,0;0,100;100,100 And so on. You control visible versus invisible vectors with the PE (pen enable) instruction: PE1, - Pen enabled, draw bright vectors. PE0, - Pen disabled, draw dark vectors. Additionally you can enter text mode with the TX instruction: TXHELLO WORLD! Will draw 'HELLO WORLD!' on the screen in the current text size and orientation. Text can be drawn at 4 sizes and in two 90-degree rotations. Basic ASCII text formatting functions are supported like CR, LE, etc. As with any analog vector generator, the 'quality' of the vector display directly reflects the finesse of the hardware designers and the quality of physical construction. Like other simlar HP equipment the HP 1350 uses top quality components and the analog design practices used are excellent, so the vectors are sharp and crisp, with well defined end points. The linearity of the analog vector circuits is excellent so the lines are very straight and the end-points match very well. Physically the HP 1350 is a small 3 1/2 tall rack-mountable box with a power switch and a few LED's on the front pannel. Inside one large PCH holds the X and Y axis accumulators and DAC's. Two smaller logic boards sit below with what appears to be the control state machine and Z axis logic on one board, and the HPIB (or optionally serial) I/O board on the other. The box is about 18 inches deep, but its rather light for its volume. I have 2 HP 1350A's and one HP 1351A, but only one of the 1350A's is operational. Both of the other machines appear to have power supply problems or are incomplete. If your HP 1350 powers up and you get the red power interupt light, try to address it and send it "20,13,10" (decimal) and it should clear the interupt led and remain in Listen, Command state. Now its ready to for commands like 'EM' to erase the display memory and begin drawing vectors. Being a totally external box, the vector display list does not take up host CPU memory like the VT-11 or Imlac PDS-1, but the host also does not have the same instant access to the display list, a pretty clear distinction between the 1350 and the other two vectors generators I'm familiar with. If your looking for a vector display system and you have a HPIB interface, I'd reccomend the HP 1350 as being quite easy to get working. I'm not sure I undersand my HPIB protocol problem just yet, but I'm using very experimental software so this is not unexpected. emanuel stiebler wrote:

On Sat, 14 Jun 2003, emanuel stiebler wrote: Well, I have a Tek 4012 terminal in San Diego that was working when it was put away a number of years ago. - don

Indeed, I find them rather fun too.... (Let's see, I have the 1350, a DEC GT40, and a Vectres (yes, I know I don't like video games, but this thing has a vector display and a 68A09 processor, so it's worth getting ;-))). One??? I have a pair of them :-) -tony