On 11/27/22 12:54, Jon Elson via cctalk wrote: If anyone cares, I've been working on a Pertec tape controller design. The initial version worked remarkably well with only a few bodge wires. I'm assembling the respin of the design and do not anticipate any issues. It's basically a 4x6 inch PCB with a bunch of through-hole TTL hooked to a piggyback MCU. I've selected the STM32F407 Chinese boards as they're inexpensive and easily available from Aliexpress, unlike a lot of the other MCU boards which seem to have been hit by the chip shortage. My current controller is getting a bit cranky and I don't want to have to rely on it. In essence, any MCU with 3 or 4 8 bit 5v tolerant GPIO ports, with one of them being bidirectional can probably work. The MCU board that I'm using has a battery-backed RTC as well as integrated SDIO. Interface to the host is pretty much dumb terminal CLI-type with data transfer to the host using good old YMODEM, using either (depending on firmware assembly) async serial or USB 2.0 FS. Transfer uses a microSD card and has been verified to work with cards of up to 64GB capacity. The file system is exFAT, so this should work with Linux, Windows, etc. I've got a bit more assembly to do and then I'll be tweaking the firmware (the STM32F407 runs at 168 MHz and has 512K of program memory, as well as 192K of SRAM onboard). To date, I've tested it on the fastest drive that I have, a Fujitsu M2444AC streamer. The 1MB/sec transfer rate doesn't appear to be a problem even at 6250 GCR. Rather than using open-collector outputs to drive the formatter interface, I'm using tristate bus buffers with drive capability of 60ma. Until the interface is initialized, the outputs float, so, in theory, multiple controllers can share the bus. Power is supplied by a 5V 2A "wall wart" supply. The reverse direction is standard TTL level, terminated with 220/300 networks. That's about all I can think of tonight. If anyone is interested, I'll put you on my email status list. Eventually, I'd like to host the whole thing on Github. A special "thank you" is due Mattis Lind, who has done a super job of PCB layout (something that gives me a raging headache). I could not have done what you did in the time that you did it! All the best, Chuck

On 2022-11-28 10:27 a.m., Jon Elson via cctalk wrote: What was the character encoding on that system? Ben.

On 11/28/22 09:27, Jon Elson via cctalk wrote: Yes, the interface to the formatter. Although, I suspect that with the current crop of MCUs, interface to the "naked" drive isn't beyond the pale--it's just that there was a considerable amount of variation in that by various vendors. My board has ICs mostly for interface. The real work is done by the MCU. I figure that a 64GB microSD should be good for at least 1,000 reels of 9 track tape. I still do that with an HP7970 equipped with the double-stack (7 and 9 track) RO heads. The naked interface goes directly to an MCU. Works well enough. I prefer naked or Pertec interface drives to SCSI because of the better control and information afforded by a more direct interface. --Chuck

On 11/29/22 13:31, Jay Jaeger via cctalk wrote: Hi Jay, The board I'm using is the STM32F4VE, described here: https://stm32-base.org/boards/STM32F407VET6-STM32-F4VE-V2.0 Cheap and available; generally about $14-15 from Aliexpress. I've toyed with the STM32H750 board (very similar, but runs at 400Mhz; the added cost didn't contribute anything toward functionality. Your DG might well be Pertec-interface, but you can check that out with Bruce Ray. Oh, a word of caution is in order... With the chip shortage, a lot of Chinese vendors are re-labeling GDS32F407 and CKS32F407 chips with the ST logo and markings. I've run into a few, but generally, they perform as well as--and in some cases, better than, the real thing. I'll put you on my mailing list... All the best, Chuck

On Sun, 27 Nov 2022, Chuck Guzis wrote: I could really use some "Unformatted to Pertec" tape controllers. I have a bunch of ½" drives but no separate formatter. So ATM they are quite useless. Christian

On Wed, Nov 30, 2022 at 4:41 PM Chuck Guzis via cctalk <cctalk(a)classiccmp.org> wrote: There is an unformatted Pertec interface, I've got at least one tape drive that uses it and have seen others. No idea if there are odd 'gotchas' between different drives though. It's 3 edge connectors, I think 0.156" pitch, all the same size (but without digging out the manuals I can't remember how many pins). Essentially, one is the write data signals, the second is the read data signals, and the third is the control signals. -tony

I have a kennedy 9100 with an unformatted pertec interface that I would love to use for imaging tapes from my AS/400 It seems like strapping a logic analyzer to the read connector, and an arduino on the command connector, may be fairly easily done? Has anyone done that? -Eric On Wed, Nov 30, 2022, 10:46 AM Jon Elson via cctalk <cctalk(a)classiccmp.org> wrote:

Arduinos are widely used, exist in a bunch of variations and sizes, are very cheap, come with a decent development environment... Don't know that one, but I guess I should look Many newer Arduinos are ARM; I've used both those and the earlier ones. For some stuff I now like to go for Raspberry Pico, which is like a more-powerful Arduino for less money. My DDCMP controller uses one of those. paul

5V tolerant does not mean 5V compatible. I have right now some 5V devices I want to control, and it's not exactly clear whether a 3.3V device will drive outputs high enough to reliably make 5V devices see them as high. Arduinos can be had in actual 5V models (5V power, standard 5V logic levels in and out). Not the fast ARM ones but for many purposes good enough. paul

On 12/1/22 05:35, Peter Corlett via cctalk wrote> A more significant issue is the substitution of 74HC for 74HCT logic in applications driven by TTL in bus applications, where the loading can be significant. Vih min tends to be around 3 volts for HC devices. Bottom line is that you may be able to get away with using an HC instead of an HCT device as a TTL bus receiver, but don't count on it always working. --Chuck

On Wed, Nov 30, 2022 at 04:43:08PM -0800, Chuck Guzis wrote: It also gives portability across manufactures for the simple stuff and a consistant though not the most feature full enviornment that is the same for each board. You can use the low level functions of the chips if you want but then it won't be portable. Also a good amount of how to do X with it online. I use it for that reason. Good for small projects. I've used manufacturer specific enviornments in the past but see no need to. Last project was some remote sensors using ESP32. $8 for the board. Arm processor.

On 12/1/22 11:02, David Gesswein via cctalk wrote: Don't a few libraries do that without saddling you with a development environment? I use opencm3 for a lot of ARM-related simplish MCU things. There was a stm32duino group, but it seems to have gone moribund. It appeared to concentrate mostly on the "blue pill" platform as well as the older Maple mini boards (anyone need any of those?) I had a brief encounter with the PIC32 Arduino Uno from Digilent, but I wasn't taken by it. --Chuck