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I remember the Video Backup System for Amiga advertized in Polish computer magazines of late 90s, "store hundreds of diskettes on a single VHS tape!"

I seriously considered buying it (and a VCR since I didn't have one...) before I got my hands on a cheap CD-ROM drive - and to this day I don't know what I have missed and if I should regret or be happy.

First, let me ask the solid objectively answerable question: it connected by SCART or RCA (composite video, "phono plug") to the VCR, but what interface did it use on Amiga side? It didn't have any built-in video, or analog inputs, so the analog data had to undergo some rudimentary conversion to digital in hardware (before being passed through Reed-Solomon Error Correction program running on Amiga). What was it?

...and then let me ask for comments, how did it work out in practice (as "user experience") - because I never knew anyone who used it, and I wonder if it was half as good as the hype in the ads.

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http://www.bigbookofamigahardware.com/bboah/product.aspx?id=776

Based on the images here, it appears the VBS used a combination of the composite out and the DB25/RS232 connector on the Amiga (as well as a connection to the monitor) to operate. I didn't own one, so I'm just interpreting the connection diagrams.

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    I'm curious as to what speed it could run. The video output could well go at a few hundred kbit/s, but the serial input is severely limited with a standard 68000 - note that Paula has no FIFO buffer and you need to reliably read one byte every 8 bits. – Zac67 Aug 8 '17 at 20:26
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    @Zac67: I'm fairly sure it didn't use RS232 protocol, just used the port as GPIO, either polling it or binding an interrupt to level change. Supposedly the limiting factor was the Reed-Solomon algorithm speed (and floppy drive if used). – SF. Aug 9 '17 at 0:52
  • @SF. Looking at the cabling, the serial port is the only way for data reading. Looking at the PCB, there's too little electronics for sophisticated data separation. The contacts visible are pins 3,7,9,10 - RxD, GND, +12V, -12V. No GPIO I guess... – Zac67 Aug 9 '17 at 8:01
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LGR (Lazy Games Review) just published an excellent review of a related VHS backup system for the PC, known as the Danmere Backer. See video on YouTube.

While I don't have any experience with the VBS for Amiga, it is shown briefly in the above video, and it appears to be similar to the external version of the Danmere Backer. According to the BBOAH page, the Amiga VBS plugged into the Amiga serial port, and the two RCA jacks on the VBS were plugged into the composite video in & out on the VCR. There would be no reason to connect the VBS to your monitor, unless you just wanted to groove out to the funky monochrome video encoding of your backup data.

  • I'm pretty sure it uses the actual composite video out of the Amiga to get the backup data to the VCR when recording, I would assume to allow higher backup speeds than the serial port would allow. bigbookofamigahardware.com/bboah/media/download_photos/vbs3.jpg – mnem Aug 12 '17 at 5:34
  • Using the Amiga's mono video out for the recording only doesn't seem practical. Whatever the data rate is, I think it would have to be the same during both recording and playback, since the VCR probably runs at the same speed for both operations. – Brian H Aug 12 '17 at 7:09
  • Also see ArVid. – Leo B. Aug 12 '17 at 14:12
  • @BrianH Good point, thinking about it you are obviously correct, the backup rate and restore rate have to be the same since the tape speed is a constant. Nevertheless, that's clearly the way it works in the connection diagram. The only reason remaining to do it that way would be to save costs creating an output circuit to take serial data and turn it into video, instead leveraging the fact that the Amiga already has everything you need to do that with its existing processing and video hardware. – mnem Aug 12 '17 at 19:43
  • I'm not sure we have a valid connection diagram for the "VBS" that I linked to on the BBOAH (which is different than the one linked in @Joe's answer). So, adding to the confusion, there's more than one product for Amiga that shares both the functionality and the descriptive name "VBS". Oy vey. – Brian H Aug 14 '17 at 3:05
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Here are the schematics. Don't know which version of VBS. http://leszczamiga.ppa.pl/elektronika/vbs.gif

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    Since this is just a single image, I suggest you embed it into your post. (You can do this using the image tool in the tool icons at the top of the editor when you edit the post.) This will ensure that the image remains in the answer even if the site currently holding it goes down. – Curt J. Sampson Sep 20 at 14:19
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    Wow! That's literally just a buffer... and that's it! So presumably the video recorder has to output RS232 from the video signal. That's either the cleverest, or the crappiest, design I've ever seen! How fast could you get the Amiga's serial port if you took over the hardware as directly as possible? What utter tripe! Good job hard disks were rarely over 20MB in those days! I wonder if the PC ISA-port version was any better? Personally I'd have used the parallel port, usually that's more open for electronic shenanigans. – Greenaum Sep 20 at 15:47
  • @Greenaum Doing a little digging around it looks like serial speeds on the Amiga are largely CPU limited (no FIFO, no DMA) for reads (you theoretically could use the copper for faster DMA writes); max stable serial input speed with a stock 68000 of approximately 38,400bps, possibly even lower if your system doesn't have any FAST RAM. Presumably that's why the VBS requirements state a minimum of a 68020 CPU and supports faster speeds on 030s and up. – mnem Sep 20 at 19:30
  • Sure. For example, using a PC here, the serial port pins connect to a serial chip, 8250 or 16550 or whatever is in the chipset there days. The parallel port though connected to a buffer chip, that the CPU could read and write directly, so software could control the parallel port pins. Til USB arrived, that was the fastest way to get data in and out, so things like scanners used it. It was as fast as software could drive it, even hard drives connected there. Bit like a fast loader on a C64. Direct pin control! So strange Amiga version used serial port. Must've been very slow! – Greenaum Sep 20 at 23:37

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