On Fri, 31 May 2024 at 10:49, Rick Troth < [email protected]> wrote:
> This kind of thing is so common. Maybe it was majic in the 1980s. But > now, everything is digital and pre-programmed at the factory. > > I have a shiny new Icom IC-7300 transceiver. (That's ham radio talk.) It > has a general coverage receiver, all modes from like 0 to somewhere past > 54MHz. But it will only *transmit* on frequencies legal to US radio > amateurs ... at the time of manufacture. > I'VE BEEN TOLD that there is a diode I can clip or remove that will > negate the transmit lockout. > Home WiFi routers generally give you a choice of your "region", which sets the frequencies the unit will transmit on. These unlicensed ranges are roughly 2.4GHz and 5 GHz worldwide, but with significant extensions at both ends of both bands for different countries. In some places the extensions used in one country overlap licensed spectrum in others. But often enough end users will choose a different region so as to get access to a less crowded frequency range. In the USA the FCC has been increasingly concerned at this, and has required these devices to have the bands not changeable by end users. But "it's all just software" in any case, and often based largely on Linux, which comes under the GPL V2. So the vendors' cheapest solution is to Tivoize* things by making the boot loader load only a signed version of the software, and then shipping versions configured for each region. The GPL V3 explicitly disallows the Tivo approach, but Linux has refused to license under V3... So in the crunch the hacker community has found flaws/bugs/opportunities for many devices to get them to boot software of their choice. * https://en.wikipedia.org/wiki/Tivoization But a bit more on topic... The 370/165 had 2 microsecond core memory (4-way interleaved), but various competitors came along with solid state replacements, which could often run somewhat faster. Turned out the 165 had a small board that contained countdown logic to wait for the memory to be ready, and by simply unplugging that board the countdown would be eliminated (or rather, reduced to the number of ticks needed for the not-yet-released /168 with solid state storage), so removing the board and plugging it back in before calling IBM for service became just a part of normal operations. Tony H. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
