Kind of a pun on the way "retro" technology can kind of "slow" your progress in other areas. Still, I'm having fun.
Started a local entropy reduction effort in the Command Cave yesterday. Maybe only 30% complete, but I made a "clean spot," so I decided to try out the HP-82163A, HP-IL video interface. A few days ago, I found the little composite video input dongle for my 32" TCL "smart" TV mounted on the wall next to my desk. Put it aside where I'd have some hope of remembering it when I got around to testing the video interface.
The biggest challenge was finding an outlet to plug the interface into. This required crawling beneath my desk, which at my age and weight is not a fun thing to do. Happy to know I could still get up afterward! Power connected, I plugged in the composite video cable, and the two HP-IL cables. I only have two, and they're the 5-meter cables, which are insanely long. So if I want to connect the printer or the tape drive as well as the video interface, I'll need to buy some more. They're very pricey on eBay, but I'll keep an eye out.
With nearly everything connected, I then learned I had to configure the TV to recognize the composite video interface, because the TV is, you know, "smart."
I grabbed the HP-71b first, because it was small and near to hand and has a more sophisticated HP-IL interface than the HP-75. Plugged in the HP-IL cables (again, happy that my 71 came with the HP-IL module, that's pretty pricey too), turned it on and Boom!
Text on the TV!
I think it's like 20 lines of 32 characters, so it's smaller than even the Apple II's 40-column, 24-row text screen. But it's a huge improvement over the single line of LCD characters built into the device.
So then I grabbed the HP-75 and plugged it in and... nothing.
I think I have to tell it to look for the interface. I started reading the docs, but then got distracted. Surprise.
The original HP-75 I bought with the tape drive and thermal printer doesn't seem to want to run on batteries. I bought a replacement battery pack that uses ordinary AAAs in lieu of the NiCads it originally shipped with, and checked the voltage on the terminals and it seems fine. Computer runs fine on AC power, but won't on battery. I'm guessing there may be a capacitor shot in there somewhere.
Well, as it happens, I had bought another HP-75, this one a "D" model, badged "AT&T Information Systems," with the barcode wand interface (but no wand), and the "Pod." It's an enclosure for the computer that includes a 300baud modem (Novation chipset, of Apple-Cat II fame.), and 64KB of battery-backed RAM storage! That was only $149!
That computer runs fine on the battery pack in the Pod. I put the original 75 in the Pod, thinking maybe it'd work on battery from the Pod. It doesn't, so I put the AT&T one back in it, but not before making sure the AT&T 75 runs on batteries outside the Pod. (I had to use the battery cover from the other HP-75, since the battery pack is actually removed when it's mounted in the Pod, and a part of the Pod itself occupies that space.)
Anyway, I started looking for the docs on the interface and the computer. I have one of those HHC thumb-drive archives, found here, that contains nearly everything ever written about these devices and... Oh, shiny!
Yeah, didn't get very far. But, I did verify that at least the 64K RAM mass storage is still accessible. So that's very convenient. Don't have to worry about whether or not the tape drive works, or I have cables. Don't have to mess around with those magnetic "cards," (really, about 1-foot long strips). And I stumbled on an easter egg on YouTube where if you type "kubla khan" at the ">" prompt, the computer will "recite" it in the LCD.
I'm somewhat chagrined to mention that I also caved on a ROM module purchase I thought I'd talked myself out of yesterday. HP made their own modified version of VisiCalc for the 75. I couldn't imagine how you could use a spreadsheet in that one-line display. There was one up on eBay for $175, which is more than what I paid for the 75 in the Pod. So I went to bed thinking it was something I'd never use, let alone "need."
Then this morning I read an article by the lead HP programmer who built the program and decided that it was cool enough that I should own it. It was a "make offer" listing, so I offered $149 and I got it. "Fool and his money," yada, yada, yada. I should put that in a spreadsheet.
What's interesting is that the 75's OS allows you to have various "files" resident in RAM, and they made spreadsheets the same sort of thing. You can have more than one worksheet resident in RAM and make references from one sheet to another. And you can call BASIC programs from cell formulas, which also seemed pretty cool. So there are some extensions to BASIC that are specific to VisiCalc in the ROM.
I'll put that module in the AT&T 75 in the Pod to take advantage of the built-in mass storage. (64K!)
Anyway, that's me. Spending my kids' inheritance and not getting my housekeeping done...
The beat goes on.Originally posted at Nice Marmot 13:08 Friday, 25 August 2023